Java Tutorial Index

Java Tutorial Java Features C++ vs Java Java History Java Hello World Java Development Kit Java Runtime Environment Java Virtual Machine Difference between JDK, JRE, and JVM Memory Areas in Java Java Operators Java Keywords Primitive Data Types Variables

Java Loops

Java Do While Loop Java While Loop Java For Loop Java Enhanced For Loop

Java Programs

Java Basic Programs Factorial Program in Java Fibonacci Series Program in Java Prime Number Program in Java Palindrome Number Program in Java Armstrong Number Program in Java Anagram Program in Java Pattern Programs in Java Calculator Program in Java Leap Year Program in Java Addition Program in Java Number Pattern Programs in Java Star Pattern Programs in Java Package Program in Java Pyramid Program in Java Sorting Program in Java String Palindrome Program in Java Even Odd Program in Java For Loop Program in Java If Else Program in Java Switch Case Program in Java GCD Program in Java LCM Program in Java Hello Program in Java Matrix Program in Java Menu Driven Program in Java Series Program in Java Client Server Program in Java Swapping Program in Java Pig Latin Program in Java Tower of Hanoi Program in Java Recursion Program in Java Matrix Multiplication Program in Java Perfect Number Program in Java Classes and Objects in Java Example Programs String Programs in Java Array Programs in Java Constructor Program in Java Inheritance Program in Java Abstract class Program in Java Interface Program in Java Encapsulation Program in Java Polymorphism Program in Java Exception Handling Program in Java Multithreading Program in Java Thread Program in Java Collection Programs in Java ArrayList Program in Java Stack Program in Java Applet Program in Java Swing Program in Java JDBC Program in Java Program to find and replace characters on string in java Program to find the duplicate characters in a string Program to check whether a given character is present in a string or not Java Program to Print Permutations of String Java program to find frequency of characters in a string Java Program to remove duplicate characters in a string Java Program to Sort an Array of 0's, 1's, and 2’s | Dutch National Flag Problem in Java Java Program to print even and odd numbers using 2 threads Java Program to generate binary numbers Java program to count the occurrences of each character Java Program to Add Digits Until the Number Becomes a Single Digit Number Program to Implement FLAMES Game in Java Packages Program in java Pangram Program in Java Java program to print matrix in Z form CRC Program in Java Star Program in Java Structure of Java Program RMI program in Java Caesar Cipher Program in Java Java Programming certification Round Robin Scheduling Program in Java Java Program to find the smallest element in a tree Program to Find Square Root of a Number Without sqrt Method in Java Program to Find the Common Elements between two Arrays in Java Automorphic Number Program in Java Multiple Inheritance Programs in Java Prime Number Program in Java Using a Scanner Program to Reverse a Number in Java Fibonacci series program in java using multithreading

Java Sorting

Sorting Algorithms in Java Merge Sort in Java Quick Sort in Java Bubble Sort in Java Insertion Sort in Java Selection Sort in Java Heap Sort in Java Radix Sort in Java Topological Sort in Java Bucket Sort in Java Counting Sort in Java Java Program to Create Set of Pairs Using HashSet

Java OOPs Concepts

OOPs - Object Oriented Programming Objects and Classes in Java Methods in Java Java Naming Conventions Constructors in Java Java this keyword Java static keyword Inheritance in Java Aggregation in Java Java super keyword Constructor Chaining and Constructor Overloading Java Polymorphism Static and Dynamic Binding in Java Java Abstraction Abstract class in Java Interface in Java Difference between Abstract class and Interface Java final keyword Packages in Java Access Modifiers in Java Java Wrapper classes Java Numbers Java Characters Java Integer Java Boolean Java Arrays Java Command Line Arguments Java strictfp Keyword Java Enumeration Java Math

Java Strings

Java Strings Java String Methods StringBuilder in Java StringBuffer in Java Java Regular Expressions StringBuffer vs StringBuilder String vs StringBuffer String vs StringBuilder String Manipulation in Java Java String Concatenation How to Reverse a String in Java String Array in Java How to Compare Two Strings in Java How to Concatenate Two Strings in Java Why String in Immutable in Java java.lang.NumberFormatException for Input String String Pool in Java Java Generate Random String How to take String Input in Java Java String Interview Questions

Java Exceptions

Exception Handling in Java Java try catch Java throw Java throws Difference between throw and throws Java finally Java Custom Exception Java Exception Propagation

Garbage Collection

Automatic Resource Management in Java Java Garbage Collection Java finalize() Java gc() Difference between final, finally and finalize Java Garbage Collection Interview Questions

Multithreading

Multithreading in Java Process and Thread in Java Basic Terms in Multithreading Java Thread creation Thread Scheduler in Java Java Thread class DeadLock in Java

Java IO

Java IO Java Read File Java file Reader Java Buffer Reader Java file Writer Java BufferedWriter Java InputStreamReader Scanner in Java Java StringReader Java StringReader Class Java StringWriter Class Java PrintWriter Java File Java Read File Line By Line Java FileInputStream Java FileOutputStream Java Create File Java Delete File Java Open File Java Read File to String Java copy file Jar File in Java Java FileNotFoundException

Serialization

Java Serialization Java transient

Networking

Java Network Programming Java Socket Programming Java URL Java URLConnection HttpURLConnection in Java Java InetAddress Java DatagramSocket and Java DatagramPacket

AWT

Java AWT

Swing

Swing in Java

Java Collections

Collections in Java Java List Interface ArrayList in Java LinkedList in Java Vector in Java Stack in Java ArrayList vs LinkedList in Java ArrayList vs Vector in Java Java Set Interface HashSet in Java LinkedHashSet in Java TreeSet in Java Java Queue Interface PriorityQueue in Java Deque in Java ArrayDeque in Java Java Map Interface HashMap in Java LinkedHashMap in Java TreeMap in Java Dictionary in Java Hashtable in Java Properties in Java Collections class in Java Java Comparable Java Comparator Comparable vs Comparator in Java

Java Generics

Generics in Java

Java Annotations

Annotations in Java

Java JDBC

Java JDBC Tutorial JDBC Architecture Types of JDBC Drivers JDBC vs ODBC Java Database Connectivity with MySQL Java Database Connectivity with Oracle Statements in java Prepared statement in Java Resultset in java Java ResultSetMetaData DatabaseMetaData in Java Callable Statement in Java Transaction Management in Java Design of JDBC

Java Differences

Java vs DotNET Java vs JavaScript Kotlin vs Java Java vs C++ C# vs Java Java float vs double Java vs Scala Java vs Go Java vs Golang Java Extends vs Implements Java vs Node.js Static vs Non-static in Java int vs Integer in Java Java protected vs private Java vs Dot Net Stack vs Heap in Java Java Array vs ArrayList Java SE vs EE Class vs Object in Java Java vs Bedrock Difference between = = and equals ( ) in java Difference between C, C++, java HashMap Vs HashTable Checked vs Unchecked Exceptions in Java Difference between print() and println() in Java Differences between Lock and Monitor in Java Concurrency Differences between Set and List in Java Char and String differences in Java Difference between String, StringBuffer and StringBuilder in java Difference between String and Char Array in Java Differences between Byte Code and Machine Code Difference between String Tokenizer and split Method in Java Difference between JIT and JVM in Java Difference Between Data Hiding and Abstraction in Java Difference Between BufferedReader and FileReader Difference Between Thread.start() and Thread.run() Difference between Aggregation and Composition in Java Difference between Constructor and Method in Java Difference between next() and nextline() in Java Difference between Static and Instance Methods in Java Differences and Similarities between HashSet, LinkedHashSet and TreeSet in Java Different Ways to Print Exception Message in Java Different Ways to Take Input from User in Java Difference Between Access Specifiers and Modifiers in Java Difference Between Java and PHP Difference Between replace() and replaceall() in Java Difference between this and super in Java Generics vs Wildcard in Java Array Vs ArrayList in Java Difference between Fork Join Framework and Executor Service in Java Difference between Jdeps Jdeprscan in Java Difference between Wait and Notify in Java

How to

How to convert String to String array in Java How to find length of integer in Java How to get Day Name from Date in Java How to open the Java control panel How to resolve Illegal state exceptions in Java How to reverse a linked list in java How to encrypt password in Java How to calculate time complexity of any program in Java How to check version of java in Linux How to enable java in chrome How to run Java program How to set path in Java How to check the Java version in cmd How to install Java in Windows 10 How to run Java program in cmd How to add double quotes in a string in Java How to convert list to String in Java How to call a method in Java How to Set Environment Variables for Java How to sort an array in Java How to Create Immutable Classes in Java How to iterate HashMap in Java How to write Java program How to create an array in Java How to create a package in Java How to generate random numbers in Java How to input String in Java How to Create Singleton Class in Java How to sort a string in Java How to use scanner in Java How to achieve multiple inheritance in Java How to find the length of an Array in Java How to Read Java JSON file How to run Java program in Eclipse How to call a function in Java How to create array of objects in Java How to import packages in Java How to run applet Program in Java How to take Array Input in Java How to call static method in Java How to compare characters in Java How to compare dates in Java How to create a linked list in Java How to download Eclipse for Java How to get ASCII value of char in Java How to get the current date and time in Java How to handle NullPointerException in Java How to initialize string array in Java How to Install Java on MAC How to run java program in ubuntu How to find characters with the maximum number of times in a string java How to Set Java_home in Linux How to Split the String in Java with Delimiter How to take Multiple String Input in Java using Scanner class How to uninstall the Java in Ubuntu How to Update Java How to add Elements in Array in Java How to avoid deadlock in java How to Split String by Comma in Java How to remove special characters from String in Java How to remove last character from String in Java How to Read XML Files in Java How to download and install Eclipse in Windows How to Create an API in Java How to Round Double Float up to Two Decimal Places in Java How to create a mirror image of a 2D array in Java How to set timer in Java How to make Java Projects How to Create Different Packages for Different Classes in Java How to run Java program in command prompt How to run Java program in Eclipse How to calculate time difference in Java How to stop execution after a certain time in Java How to check data type in Java How to Reduce Time Complexity in Java How to check if date is valid in Java How many ways to create object in Java How to add 4 Hours to the Current Date in Java How to add 4 Years to the Current Date in Java How to add 6 Months to the Current Date in Java How to add 24 Hours to Date in Java How to Assign Static Value to Date in Java How to check Date is Greater in Java How to check Date Null in Java How to check valid date in Java How to Iterate List in Java How to increment and decrement date using Java How to Create a Generic List in Java How to compare two dates in different format in Java How to compare three dates in Java How to override toString() method in Java How to Solve the Deprecated Error in Java How to Return Value from Lambda Expression Java How to Read CSV Files in Java How to Change the Day in the Date using Java How to Calculate Week Number From Current Date in Java How to Calculate Time Difference Between Two Dates in Java How to Calculate the Time Difference between Two Dates in Java How Many Ways to Create an Object in Java How to Develop Programming Logic in Java How can we achieve abstraction in Java How to create abstract class in Java How to use api in Java

Java 8 Features

Java 8 Features Lambda Expressions in Java Functional Interface in Java Streams in Java Java Base64 Encoding and Decoding Type Annotations in Java Java Stringjoiner Class Parallel Arrays Sort in Java Bifunction in java 8 Java 8 filters list Java 8 Consumer Interface in Java

Java 9 Features

Java 9 Tutorial Java 9 Try With Resources Java 9 Interface Private Method

Java 12

What’s new in Java 12

Java 13

Java 13 New Features

Java 14

New Features of Java 14

Java 15

What’s New in Java 15

Java 16

Java 16

Java 17

What is new in Java 17

Java Math Methods

Math.abs() Math.acos() Math.addExact() Math.asin() Math.atan () Math.atan2() Math.cbrt() Math.ceil() Math.copysign() Math.cos() Math.cosh() Math.decrementExact() Math.exp() Math.expm1() Math.floor() Math.floorDiv() Math.floorMod() Math.fma() Math.getExponent() Math.hypot() Math.IEEEremainder() Math.incrementExact() Math.log() Math.log10() Math.log1p() Math.max() Math.min() Math.multiplyExact() Math.multiplyFull() Math.negateExact() Math.nextAfter() Math.nextDown() Math.nextUp() Math.pow() Math.random() Math.rint() Math.round() Math.scalb() Math.signum() Math.sin() Math.sinh() Math.sqrt() Math.subtractExact() Math.tan() Math.tanh() Math.toDegrees() Math.toIntExact() Math.toRadians() Math.ulp() Math.multiplyExact()

Java String Methods

toCharArray() copyValueOf() endsWith() equals() equalsIgnoreCase() format() getBytes() getChars() hashCode() indexOf() intern() isEmpty() join() lastIndexOf() length() replace() replaceAll() replaceFirst() split() startsWith() subSequence() substring() toLowerCase() toUpperCase() trim() valueOf()

Java Conversion

Java Convert String to int Java Convert int to String Java Convert String to long Java Convert long to String Java Convert String to float Java Convert float to String Java Convert String to double Java Convert double to String Java Convert String to Date Java Convert Date to String Java Convert String to Object Java Convert Object to String Java Convert String to char Java Convert char to String Java Convert int to long Java Convert long to int

Java Keywords

Reserved Keywords in Java Java Case Keyword Java Class Keyword Java Continue Keyword Java Default Keyword Java Double Keyword Java Else Keyword Java Enum Keyword Java Extends keyword Java Finally Keyword Java Char Keyword Contextual keywords in Java Java Break Keyword Volatile keyword in Java Java Boolean Keyword Java Byte Keyword The final Keyword in Java Java For Keyword Java Float Keyword Java Instanceof Keyword Java If Keyword Java Int Keyword Java Import Keyword Java Package Keyword Java Static Keyword Java Public Keyword Java Implements Keyword Java Private keyword Java Protected Keyword Java Short Keyword Java Long Keyword Java Interface Keyword Java Try Keyword Java New Keyword Java Return Keyword Java Null Keyword this keyword in Java Java Strictfp Keyword Java Switch Keyword Java Transient Keyword Java Volatile Keyword Java While Keyword Java Throw and Throws Keyword Synchronized Keyword in Java Java Super Keyword

Java Problems

3N+1 problem program in Java Ad Hoc Problem on Arrays in Java Alice and Bob Problem Java Alien language problem in Java Bin Packing Problem Java flour pack problem in Java Hourglass problem in Java Activity selection problem in Java Bounded buffer problem in Java Diamond problem in Java Dutch National Flag Problem in Java Monsoon Umbrella Problem in Java Producer consumer problem in Java using Synchronised block Coin change problem in dynamic programming Salesman Problem in Java Sleeping Barber Problem in Java Skyline Problem in Java Sliding Window Problem in Java Snake and Ladder Problem in Java Stable Marriage Problem in Java Davis Staircase Problem in Java Graph Problems in Java Sales Tax Problem in Java Stock Span Problem Using Stack in Java

Java Questions

What are Array strings in Java What is String in Java? What is string in Java why it's immutable What is advance Java? What is interpreter in Java? What is anagram in Java? How Many Ways to Create Objects in Java How annotations work in Java What is Core Java Why to use Enum in Java Can we override Private Method in Java Can Abstract Classes have Static Methods in Java What is the ambiguity problem in Java Can we create object of abstract class in Java Why do we use abstract class in Java

Java Interview Questions

Enum Java Interview Questions Java concurrency interview questions String Coding Interview Questions in Java

Misc

List all files in a Directory in Java Nonagonal number in Java Null Pointer Exception in Java Package naming convention in Java PriorityBlockingQueue Class in Java Race Condition in Java Repdigit Numbers in Java Rotate matrix by 90 degrees in Java Segment Tree in Java Sierpinski Number in Java Sort Dates in Java Thread Safety and How to Achieve it in Java Normal and Trace of a Matrix in Java Transient variable in Java Tribonacci series in Java Web Crawler in Java Zigzag Traversal of Binary Tree in Java Java Full Stack Java IO filenotfoundexception Java Output Formatting Java Plot Java Pop Java Set to List Java Switch string Java Thread Lifecycle: States and Stages Java Viva Questions and Answers Lazy Propagation in Segment Tree in Java Level order Traversal of a Binary Tree in Java Method chaining in Java Narcissistic Number in Java Java Try-Catch Block Java CountDownLatch Java Editors Java Font Example of Static import in Java Implementing Queue Using Array in Java Instanceof operator in Java Interchange Diagonal elements in Java Java Arrays Fill Convert list to array Java Convert milliseconds to date in Java Copy data/content from one file to another in java Creating a Jar file in Java Crown Pattern in Java Duodecimal in Java Finding middle node of a linked list in Java Group by in Java 8 Hollow Diamond Pattern in Java Java Boyer Moore Catalan number in Java Cosmic Superclass in Java Fall through in Java Figurate Number in Java Java Anon Proxy Java RMI Lazy loading in Java Magnanimous Number in java Shallow copy in Java String to JSON in Java Tetranacci Number in Java Vigesimal in Java Why main method is static in Java Add Time in Java Bellman Ford Algorithm in Java Best Java Libraries Blockchain in Java Blocking Queue in Java Example Bully Algorithm code in Java Convert JSON File to String in Java Determine the Upper Bound of a Two-Dimensional Array in Java Java.net.ConnectionException Java.net.SocketException Web Service Response Time Calculation in Java Functional Interfaces in Java Singleton class in Java Awesome explanation of Strings in Java Object class in Java Static class in Java All the important string methods in Java String Handling Method in Java Advantages and Disadvantages of Strings in Java Big Decimal class in Java Class definition in Java Replace character in string Java String isnullorempty in Java String Matches in Java Trim Method in String Java Bean class in Java Libraries in Java Arithmetic Operations on String in Java Convert Char array to string in java Check whether Java is installed or not Jagged Array in Java Java ArraylistRemove() Time Complexity Java Swing Time Picker Zigzag Array in Java Array and String based questions in Java Array and String with Examples in Java Best Practices to use String Class in Java Java String Java String Inbuilt functions Java String Matches vs Contains Sum of digits in string in java Check the presence of Substring in a String in java Java import packages Interfaces and Classes in Strings in Java Maximum length of string in java Hidden classes in Java Class memory in Java public static void main string args meaning in java Reverse a String in Java String Concatenation in Java Buffer reader to read string in Java Split String into String Array in Java Reverse a String using Collections in Java Upcasting and Downcasting in Java String Declaration in Java Method Overloading In Java Java Solid Principles Java Architecture Binary Search Java Java Type Casting Java Pass-by-Reference Java Framework List Java Destructors Java Control Statements Java Byte Code Java Beans Java Identifiers Character Array in Java Java Applications Java Substring Java Session Non-primitive data types in Java Matrix Multiplication in Java JIT in Java Java Tokens Java Externalization Default Virtual Behaviour in C++ vs Java Why we use static in Java Session Tracking in Java Knapsack problem in Java Java Logo Java exception list Java Iterator Java instance variable Frugal number in Java Fork Join in Java Date time API in java Compile time vs Runtime in java Compare time in java AES 256 Encryption in Java Advanced Java skills User Defined Exception in Java Upcasting in Java Tree Implementation in Java Special Operators in Java Reentrant Lock in Java Perfect Number in Java Java logger Java LinkedList vs ArrayList File Operation in Java Constructor Overloading in Java Conditional operator in Java Concurrent Linked Deque in Java with Examples Command Class in Java Best Java IDE Association in Java Access specifiers in Java AbstractSet Class in Java Adapter class in Java Composition in Java Mutable and Immutable in Java Static() Function in Java Traverse through HashMap in Java Vectors in Java Creation of Multi Thread in java Compile-time Error in Java Java Get Time in UTC Java.sql.Time Format Thread Concept in Java Enterprise Java Beans POJO in Java Java Constant Collection Interfaces in Java with Examples Deadlock Prevention and avoidance in Java Java List Implementations Java Xml Parser Method Overriding in Java Virtual Function in Java Advanced Java Viva Questions Application of Array in Java Economical number in Java Iterate JSON array in Java Java callable example Java Command not found Java Date add Days Java File Extension Java Location Java Trim User Defined Custom Exceptions in Java Java array list remove time complexity Java.lang.Exception.NoRunnableMethods Java Map Example Java Obfuscator Java Pi Java Queue Java time local date Java Xmx Uses of Java Applet Life Cycle in Java Best Java Security Framework BigDecimal toString() in Java Jdoodle Java Literals in Java MVC in Java Powerful Number in Java Read the XLSX file in Java Relatively Prime in Java Root exception in java Accessors and Mutator in Java Bottom view of a binary tree in Java Convert List to String in Java Equidigital in Java IdentityHashMap in Java Java Clone Array Java LDAP Authentication Java List Node Java Password Generator Magic Square in Java Pancake Sorting in Java Practical Number in Java Sublime Number in Java Sudoku in Java Compare Two Times in Java Diffie Hellman Algorithm in Java Java calculate age Map of Map in Java Minimum XOR value pair in Java Palindrome Partitioning problem in Java Pernicious Number in Java Prime Points in Java Rectangular Numbers in Java Sleep Time in Java Types of Statements in Java Unicode System in Java Zig Zag star and Number Pattern in Java Balanced Prime Number in Java ConcurrentSkipListSet in Java Construct the Largest Number from the Given Array in Java CopyOnWriteArrayList in Java Cyclic Barrier in Java Dangling Else problem in Java Display Unique Rows in a Binary Matrix in Java Empty Statement in Java Factorial of a Large Number in Java Facts about null in Java Rehashing in Java Singleton Design Pattern in Java Zebra Puzzle Problem in Java XOR of Array Elements Except Itself in Java Types of Sockets in Java Thread Synchronization in Java Set Up the Environment in Java Method and Block Synchronization in Java Fibodiv Number in Java House Numbers in Java GCD of Different SubSequences in Java Hogben Numbers in Java Decagonal Numbers in Java Converting Roman to Integer Numerals in java Check if the given array is mirror inverse in Java Block Swap Algorithm for array rotation in Java Java Binary Tree Binary Strings Without Consecutive Ones in Java Beautiful Array in Java Balanced Parentheses in Java Arithmetic exception in Java Add numbers represented by Linked Lists in Java Two Decimal Places Java Intersection Point of two linked list in Java Find next greater number with same set of digits in Java Getter and Setter Method in Java Example Java Binary to Hexadecimal Java Calculate Average of List Iccanobif Numbers in Java Java delete directory Tug of War in Java Types of Events in Java MessageDigest in Java Longest Odd Even Subsequence in Java Java Variable Declaration Java Technologies List Java Localization Java Linters Java Macros Java Future Example Nth node from the end of the Linked list in Java Moran Numbers in Java Missing Number in an Arithmetic Progression in Java Minimum Window Subsequence in Java Minimum Number of Taps to Open to Water a Garden in Java Minimum Number of Platforms Required for a Railway Station Minimum Difference Between Groups of Size Two in Java Java SHA256 Java Snippets Java Speech Recognition Java Subtract Days from Current Date Java Project Ideas Majority Element in Java Longest Arithmetic Progression Sequence in Java Object Definition in Java Print Matrix Diagonally in Java Print Pencil Shape Pattern in Java Sparse Numbers in Java Split the Number String into Primes in Java Sylvester Sequence in Java Three Partition Problems in Java Banking Application in Java Brilliant Number in Java Convert Integer to Roman Numerals in Java Chromatic Number in Java Convert JSON to Map in Java Arrow Operator in Java Converting Long to Date in Java Count of Range Sum Problem in Java Finding Odd Occurrence of a Number in Java Generic queue in Java Hamming Code in Java Hashing Algorithm in Java Heap Implementation in Java Hybrid Inheritance in Java Internal Working of ArrayList in Java Java Binary Operators Java BLOB Java Coding Software Maximizing Profit in Stock Buy Sell in Java Median Of Stream Of Running Integers in Java Misc Operators in Java Nth Term of Geometric Progression in Java Self-Descriptive Numbers in Java Permutation Coefficient in Java Minimum Lights to Activate Java Snippet Class Java Console Java Developer Java Get File Size Java Image Java Interface Lock Java OCR Least Operator to Express Number in Java List of Constants in Java Loose Coupling in Java Order of Execution of Constructors in Java Inheritance Shift right zero Fill Operator in Java and Operator Shifting Shopping Bill in Java Sort Elements by Frequency in Java Spliterator in Java 8 Static Array in Java Ternary Operator in Java Tetris Game in Java Cast Operator in Java This Operator Using in Java Thread States in Java Tilde operator in Java Timestamp Operation in Java Untouchable Number in Java Various Operation on Queue using Linked List in Java Various operations on HashSet in Java Why are generics used in Java XOR Binary Operator in Java Anonymous Function in Java Flag Pattern in Java Ganesha’s Pattern in Java Heart Pattern in Java Getting Synchronized Set from Java HashSet India Map Pattern in Java InputMismatchException in Java Java Generate UUID Java Lock Java Thread Priority in Multithreading Lombok Java Morris Traversal for Inorder in Java Morris Traversal for Preorder in Java Ordinal Number in Java Polygonal Number in Java Sealed Class in Java Set Matrix Zeros in Java Swastika Pattern in Java Centered Square Numbers in Java Array Slicing in Java Block Swap Algorithm for Array Rotation in Java Bouncy Number in Java Byte to Hex in Java Camel Case in Java Bad Operand types for Binary Operator Java Comparetoignorecase in Java Creating API Document Javadoc tool Advantages of Generics in Java Computing Digit Sum of all Numbers from 1 to n in Java ConcurrentModificationException in Java Check Whether A Number Is A Power Convert IP to Binary in Java Creating a Custom Generic Class in Java Get year from date in Java Gregorian Calendar Java Current Date Grepcode Java util date Hierarchy of operators in Java Highest precedence in Java Java Map Generic Java Lambda foreach Java copy constructor Example Java Imageio Java Generics Questions Java extend multiple classes Getting the Day from the Date in Java Get yesterdays date by no of days in Java Dining Philosophers problem in Java Display List of TimeZone with GMT and UTC in Java Equilibrium Index of an Array in Java Find the Frequency of Each Element in the Array in Java Find Unique Elements in Array Java Stone Game in Java System Class in Java The Diamond Operator in Java 7 The Maximum Rectangular Area in a Histogram in Java Three-way operator in Java Types of Assignment Operators in Java Trimorphic numbers in Java Types of Bitwise Operators in Java Types of Garbage Collector in Java Types of Logical Operators in Java Union in Java URLConnection class in Java Use Of Adapter class in Java Various operations on the Queue using Stack in Java XNOR operator in Java Zygodromes in Java Memory Leak in Java Java Worker Class Java Sort String Local Minima in Java Mutable class in Java MOOD Factors to Assess a Java Program Model Class in Java Manachers Algorithm in Java Logger class in Java && operator in Java nth Prime Number in Java SHA Decrypt in Java Producer Consumer Problem in Java Using Synchronized Block Ramanujan Number or Taxicab Number in Java Undo and Redo Operations in Java Second Smallest Number in an Array in Java Set Value to Enum in Java Java Code Coverage Tools Console Errors in Java Java md5 Hash Example If Condition in Lambda Expression Java Java Code Optimization Java Enum Java Error Stack Trace Java Flags Enum Java Heap Space Out of Memory Error Java Thread Dump Analyzer Kong Java Client Nested Enum in Java Switch Case with Enum in Java Time Class Operation in Java Delete a Cycle from a Linked List in Java Java Append Data to File Java RandomAccessfile Java Rename File Java Swings Java Try Resource Java Write File Java Maven Silicon Modules in Golang Creating a file using multithreading in Java Different ways to do multithreading in Java File handling using multithreading in Java Four player card game Java Multithreading Getting first date of month in Java Implicit Typecasting in Java Importance of thread synchronization in Multithreading in Java Java lambda filter example Java Memory Model Multithreading Java Sleep Java tricky code snippets Multithreaded lru cache in Java Neon Number in Java Prime number using multithreading in Java Read large xml file in Java multithreaded Role of join function in multithreading in Java String reverse preserving white spaces in Java Use of abstract method in Java Java Abstract factory pattern Java Single Linkedlist Abstract Declaration in Java Abstract Factory in Java Abstract for java mini project Abstract for Java project Advantages of abstraction in Java AWS Lambda Java Maven Adding Manychat Java Snippet to Thrive Theme Abstract implement interface in Java Addition Program Call by Reference Using Multithreading in Java Advanced Java Code Snippets Advantages of Multithreading Over Multitasking in Java Apache Camel Multithreading in Java Array of Class Objects in Java Autobiographical Number in Java AWS lambda Java example api gateway AWS Lambda Java Gradle AWS Lambda Java SDK AWS Lambda Java Spring Boot AWS Lambda Java Tutorial AWS Lambda REST API Java Benefits of Multithreading in Java Boundary Value Problem ODE in Java 2d Array Sorting in Java A Group Chat Application in Java Access Modifiers For Classes or Interfaces in Java Card Flipping Game in Java Duplicate Class Error in Java Giuga Numbers in Java Java Integer Reverse Method Methods Of GSon in Java Selection Statement in Java Dead Code in Java Find the index of an Array Element in Java K Closest Points to a Given Target Point in Java Last Non Zero Digit of a Factorial in Java Meta Class in Java Unreachable Code Error in Java Angle Bracket <> in Java with Examples Different types of Recursions in Java Java Lambda Filter Example Java Program for Shopping Bill Pythagorean Triplet with Given Sum Using Single Loop in Java TemporalAdjusters lastInMonth() method in Java with Examples ZIP API in Java Atomic reference in Java Digit Extraction in Java DRY (Don't Repeat Yourself) Principles in Java with Examples Empty array in Java Is main method compulsory in Java? Java I/O Operation - Wrapper Class vs Primitive Class Variables Java Program to Find the Perimeter of a Rectangle Java Thread Priority Java Type Erasure Need of Concurrent Collections in Java Nested ArrayList in Java Print Odd and Even Numbers by Two Threads in Java Square pattern in Java TemporalAdjusters next() method in Java with Examples What does start() function do in multithreading in Java Convert Number to Words Problem in Java Detect And Remove Cycle in a Single Linked List in Java Evolution of Interfaces in Java How to pad a String in Java Implementing Patricia Trie in Java Java Program to Find the Most Repeated Word in a Text File java.util.UUID class in Java ReadWriteLock Interface in Java Reference Data Types in Java Sort An Array According to The Count of Set Bits in Java Alternate Vowel and Consonant string in Java Built-in Exceptions in Java with Examples Capture the Pawns Problem in Java Collections.shuffle() Method in Java with Examples JDBC MySQL Localhost 3306 Alternate Vowel and Consonant string in Java Built-in Exceptions in Java with Examples Capture the Pawns Problem in Java Collections.shuffle() Method in Java with Examples Convert Number to Words Problem in Java Detect And Remove Cycle in a Single Linked List in Java Evolution of Interfaces in Java How to pad a String in Java Implementing Patricia Trie in Java Java Program to Find the Most Repeated Word in a Text File java.util.UUID class in Java ReadWriteLock Interface in Java Reference Data Types in Java Sort An Array According to The Count of Set Bits in Java JDBC MySQL Localhost 3306 Adding a Character as Thousands Separator to Given Number in Java Circular Primes in Java Equilibrium Index Problem in Java Java String regionMatches() Method with Examples LFU Cache Problem in Java Longest Repeating and Non-Overlapping Substring in Java Prefix Suffix Search in Java Product Array Puzzle Problem in Java Russian Doll Envelopes Problem in Java Second Most Repeated Word in a Sequence in Java Special Two-Digit Numbers in a Binary Search Tree in Java Swap Corner Words and Reverse Middle Characters in Java Toggle K bits Problem in Java Upside Down Binary Tree in Java Verbal Arithmetic Puzzle Problem in Java Insert a String into another String in Java Print Shortest Path to Print a String on Screen in Java Search Insert Position in Java BST Sequences in Java Burrows - 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Types of Classes in Java

Java is a widely-used programming language that is popular among developers due to its versatility and ease of use.  It is an Object-oriented programming language that is widely used to build various applications. One of the key features of Java is its support for classes, which are templates for creating objects. Classes are a fundamental component of Java that allow developers to define objects and their characteristics.

There are seven types of classes in Java that have different properties and purposes.

  1. Static Class
  2. Final Class
  3. Abstract Class
  4. Concrete Class
  5. Singleton Class
  6. POJO Class (Plain Old Java Object)
  7. Inner Class (Non-static Nested Class)

1.Static Class:

In Java, a static class is a nested class that has the "static" keyword in its definition. Unlike non-static nested classes, static classes can be accessed without creating an instance of the enclosing class. It is because a static class is not associated with any instance of the enclosing class.

Syntax:

public static class MyStaticClass {
    // static methods and fields go here
}

Purpose:

  1. Static classes are commonly used to group related functionality together. By defining related methods and fields in a single static class, code organization can be improved.
  2. Since a static class does not require instantiation, it can help improve performance by reducing the number of objects created.
  3. Similar to the previous point, the lack of instantiation required for static classes also helps reduce memory usage.
  4. Static classes can be used to create helper classes that provide a set of related methods. These helper classes can be used in conjunction with the main class to provide additional functionality.
  5. Java's utility classes often consist of static classes. These utility classes provide a set of commonly used functions for developers to use without needing to implement them from scratch.

Properties:

  1. A static class is a nested class that has the "static" keyword in its definition.
  2. Static classes can be accessed without creating an instance of the enclosing class.
  3. Static classes cannot access non-static members of the enclosing class.
  4. Static classes can have static fields, methods, and nested classes.

ALGORITHM:

Step 1: Define a public class called "StaticClassExample".

Step 2: Define the main method within the "StaticClassExample" class.

Step 3: Call the static "add" method of the "StaticMath" class with the arguments 2 and 3 and assign the result to a variable called "result".

Step 4: Print out the value of the "result" variable.

Step 5: Attempt to create an instance of the "StaticMath" class (which is not allowed because the class is static), and comment out this line of code to prevent a compilation error.

Step 6: Define a static class called "StaticMath" within the "StaticClassExample" class.

Step 7: Define a static method called "add" within the "StaticMath" class that takes two integer arguments and returns their sum.

End the program.

Implementation:

FileName: StaticClassExample.java

import java.util.*;
public class StaticClassExample {


    public static void main(String[] args) {
        // Call the static method of the static class without creating an instance
        int result = StaticMath.add(2, 3);
        System.out.println("Result: " + result);
        
        // Attempt to create an instance of the static class (which is not allowed)
        // This line of code will result in a compilation error
        // StaticMath math = new StaticMath();
    }


    // A static class with a static method
    static class StaticMath {
        
        // A static method that adds two integers and returns the result
        public static int add(int a, int b) {
            return a + b;
        }
        
    }


}

Output:

Result: 5

2.Final Class:

In Java, a final class is a class that cannot be extended or subclassed. It means that once a final class is defined, it cannot be further modified or extended by any other class. Final classes are often used in Java to ensure that a class cannot be modified, ensuring its stability and consistency. To define a final class in Java, the "final" keyword is used in the class definition.

Syntax:

final class MyFinalClass {
   // code goes here
}


Purpose:

  1. Final classes are often used to ensure the stability and consistency of a class. By preventing subclasses from modifying or extending a class, a final class can ensure that its behavior and implementation remain consistent over time.
  2. Final classes can help to improve performance by allowing the JVM to optimize the class's methods and fields for better performance.
  3. Final classes are often used to create immutable classes. Immutable classes are classes whose instances cannot be modified once they are created. By defining a final class with final fields, an immutable class can be created that is thread-safe and guarantees that its instances remain consistent over time.
  4. Final classes can be used to prevent subclassing and ensure that the class's functionality remains unchanged. It is useful in situations where the class is intended to be used as is and should not be modified or extended.
  5. Final classes can be used to ensure security by preventing subclasses from modifying or extending a class in ways that could compromise security.

Properties:

  1. A final class is a class that cannot be extended or subclassed.
  2. All the methods and fields of a final class are implicitly final.
  3. Final classes cannot be modified or extended by any other class.
  4. Final classes are often used to create immutable classes.

ALGORITHM:

Step 1: Define a final class ImmutablePerson with three private final instance variables firstName, lastName, and age.

Step 2: Define a constructor that sets the values of these instance variables.

Step 3: Define getter methods for each instance variable.

Step 4: Create a public class FinalClassExample to test the ImmutablePerson class.

Step 5: Create an instance of the ImmutablePerson class and initialize it with values for firstName, lastName, and age.

Step 6: Attempt to modify the instance variables (which is not allowed).

Step 7: Print out the values of the instance variables using the getter methods.

FileName: FinalClassExample.java

import java.util.*;
// Define a final class that cannot be subclassed
final class ImmutablePerson {
    
    // Declare private final instance variables to ensure immutability
    private final String firstName;
    private final String lastName;
    private final int age;
    
    // Define a constructor to set the values of the instance variables
    public ImmutablePerson(String firstName, String lastName, int age) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }
    
    // Define getter methods for the instance variables
    public String getFirstName() {
        return firstName;
    }
    
    public String getLastName() {
        return lastName;
    }
    
    public int getAge() {
        return age;
    }
}


// Create a public class to test the final class
class FinalClassExample {
    
    public static void main(String[] args) {
        
        // Create a new instance of the immutable person class
        ImmutablePerson person = new ImmutablePerson("John", "Doe", 30);
        
        // Attempt to modify the instance variables (which is not allowed)
        // This line of code will result in a compilation error
        // person.firstName = "Jane";
        
        // Print out the values of the instance variables
        System.out.println("First Name: " + person.getFirstName());
        System.out.println("Last Name: " + person.getLastName());
        System.out.println("Age: " + person.getAge());
    }
}

Output:

First Name: John
Last Name: Doe
Age: 30

3.Abstract Class:

In Java, an abstract class is a class that is declared with the "abstract" keyword in its definition. An abstract class is not intended to be instantiated on its own, but rather serves as a base class for its subclasses to inherit from. Abstract classes can define method signatures without providing the method implementation, which is then implemented by the subclass.

Purpose:

  1. To define a common interface or behavior that can be shared by a group of related classes.
  2. To provide a template or blueprint for creating concrete classes that inherit from it.
  3. To enforce a contract or set of rules that any subclass must adhere to by defining a set of abstract methods that the subclass must implement.
  4. To allow for the extension of functionality in a program without modifying existing code, by adding new concrete subclasses that inherit from the abstract class.
  5. To facilitate polymorphism in a program, where objects of different concrete classes can be treated as instances of the same abstract class.
  6. To abstract away implementation details and provide a higher-level view of a class hierarchy, making the code more maintainable and easier to understand.
  7. To separate the interface from the implementation of a class, allowing for more flexibility in changing the implementation without affecting the interface.

Properties:

  1. An abstract class cannot be instantiated directly. It can only be used as a superclass for other concrete or abstract classes.
  2. An abstract class may or may not contain abstract methods.
  3. An abstract class can have constructors and instance variables.
  4. An abstract class can have both abstract and non-abstract methods.
  5. An abstract class can be used as a type for references and variables.

ALGORITHM:

Step 1: Define an abstract class Shape with protected instance variables color and filled, a constructor to set these values, abstract methods to get area and perimeter, and getter and setter methods for the instance variables.

Step 2: Define a subclass of Shape called Circle with a private instance variable radius, a constructor to set the values of the instance variables, implementations of the abstract methods to calculate area and perimeter, and a toString() method to display information about the circle.

Step 3: Define a subclass of Shape called Rectangle with private instance variables length and width, a constructor to set the values of the instance variables, implementations of the abstract methods to calculate area and perimeter, and a toString() method to display information about the rectangle.

Step 4: Create a public class called AbstractClassExample to test the Shape, Circle, and Rectangle classes.

Step 5: In the main method of AbstractClassExample, create a new instance of the Circle class and display information about the circle.

Step 6: Create a new instance of the Rectangle class and display information about the rectangle.

Step 7: Change the color and filled status of the rectangle using setter methods.

Step 8: Display updated information about the rectangle.

FileName: AbstractClassExample.java

import java.util.*;
// Define an abstract class to represent a shape
abstract class Shape {
    
    // Declare protected instance variables to be used by subclasses
    protected String color;
    protected boolean filled;
    
    // Define a constructor to set the values of the instance variables
    public Shape(String color, boolean filled) {
        this.color = color;
        this.filled = filled;
    }
    
    // Define abstract methods that must be implemented by subclasses
    public abstract double getArea();
    public abstract double getPerimeter();
    
    // Define getter and setter methods for the instance variables
    public String getColor() {
        return color;
    }
    
    public void setColor(String color) {
        this.color = color;
    }
    
    public boolean isFilled() {
        return filled;
    }
    
    public void setFilled(boolean filled) {
        this.filled = filled;
    }
    
    // Define a toString() method to display information about the shape
    public String toString() {
        return "Shape[color=" + color + ",filled=" + filled + "]";
    }
}


// Define a subclass of Shape to represent a Circle
class Circle extends Shape {
    
    // Declare private instance variable to represent the radius of the circle
    private double radius;
    
    // Define a constructor to set the values of the instance variables
    public Circle(String color, boolean filled, double radius) {
        super(color, filled);
        this.radius = radius;
    }
    
    // Implement the abstract methods of the Shape class to calculate the area and perimeter of the circle
    public double getArea() {
        return Math.PI * radius * radius;
    }
    
    public double getPerimeter() {
        return 2 * Math.PI * radius;
    }
    
    // Define a toString() method to display information about the circle
    public String toString() {
        return "Circle[" + super.toString() + ",radius=" + radius + "]";
    }
}


// Define a subclass of Shape to represent a Rectangle
class Rectangle extends Shape {
    
    // Declare private instance variables to represent the length and width of the rectangle
    private double length;
    private double width;
    
    // Define a constructor to set the values of the instance variables
    public Rectangle(String color, boolean filled, double length, double width) {
        super(color, filled);
        this.length = length;
        this.width = width;
    }
    
    // Implement the abstract methods of the Shape class to calculate the area and perimeter of the rectangle
    public double getArea() {
        return length * width;
    }
    
    public double getPerimeter() {
        return 2 * (length + width);
    }
    
    // Define a toString() method to display information about the rectangle
    public String toString() {
        return "Rectangle[" + super.toString() + ",length=" + length + ",width=" + width + "]";
    }
}


// Create a public class to test the Shape, Circle, and Rectangle classes
class AbstractClassExample {
    
    public static void main(String[] args) {
        
        // Create a new instance of the Circle class
        Circle circle = new Circle("Red", true, 5.0);
        
        // Display information about the circle
        System.out.println(circle);
        System.out.println("Area: " + circle.getArea());
        System.out.println("Perimeter: " + circle.getPerimeter());
        
        // Create a new instance of the Rectangle class
        Rectangle rectangle = new Rectangle("Blue", false, 4.0, 6.0);
        
        // Display information about the rectangle
        System.out.println("Rectangle");
        System.out.println("Area: " + rectangle.getArea());
        System.out.println("Perimeter: " + rectangle.getPerimeter());
            // Change the color and filled status of the rectangle
    rectangle.setColor("Green");
    rectangle.setFilled(true);
    
    // Display updated information about the rectangle
    System.out.println("Updated Rectangle");
    System.out.println(rectangle);
    System.out.println("Area: " + rectangle.getArea());
    System.out.println("Perimeter: " + rectangle.getPerimeter());
}
}

Output:

Circle[Shape[color=Red,filled=true],radius=5.0]
Area: 78.53981633974483
Perimeter: 31.41592653589793
Rectangle[Shape[color=Blue,filled=false],length=4.0,width=6.0]
Area: 24.0
Perimeter: 20.0
Updated Rectangle
Rectangle[Shape[color=Green,filled=true],length=4.0,width=6.0]
Area: 24.0
Perimeter: 20.0

4.Concrete Class:

In Java, a concrete class is a class that has a complete implementation and can be instantiated to create objects. Unlike an abstract class, a concrete class can be instantiated directly and can be used to create objects. It provides a full implementation of all its methods and can be used to define objects that can interact with other objects in a Java program.

Purpose:

  1. Provides a specific implementation for an abstract or generic concept defined by an interface or abstract class.
  2. Allows for code reuse by defining common functionality in a superclass or interface and implementing it in multiple subclasses.
  3. Provides a way to encapsulate data and behavior within a single entity, improving modularity and organization in code.

Properties:

  1. Can be instantiated to create objects.
  2. Implements all the methods declared in its interface or superclass.
  3. May define additional methods and variables specific to its functionality.

ALGORITHM:

Step 1: Create a new Java class called "Car"

Step 2: Declare the private instance variables "make", "model", and "year" as String and int respectively

Step 3: Define a constructor with parameters "make", "model", and "year" to initialize the instance variables

Step 4: Define getter and setter methods for each of the instance variables

Step 5: Define a method called "displayCarInfo" to display the make, model, and year of the car

Step 6: Define a main function to test the Car class

Step 7: Create a new Car object with the make "Toyota", model "Camry", and year 2020

Step 8: Call the "displayCarInfo" method on the Car object to display its information

Step 9: Use the "setMake" method to change the make of the car to "Honda"

Step 10: Call the "displayCarInfo" method again to display the updated information about the car

FileName: Car.java

import java.util.*;


// Define a Concrete class to represent a Car
public class Car {
    // Declare private instance variables to represent the make, model, and year of the car
private String make;
private String model;
private int year;


// Define a constructor to set the values of the instance variables
public Car(String make, String model, int year) {
    this.make = make;
    this.model = model;
    this.year = year;
}


// Define getter and setter methods for the instance variables
public String getMake() {
    return make;
}


public void setMake(String make) {
    this.make = make;
}


public String getModel() {
    return model;
}


public void setModel(String model) {
    this.model = model;
}


public int getYear() {
    return year;
}


public void setYear(int year) {
    this.year = year;
}


// Define a method to display information about the car
public void displayCarInfo() {
    System.out.println("Make: " + make);
    System.out.println("Model: " + model);
    System.out.println("Year: " + year);
}


// Main function to test the Car class
public static void main(String[] args) {
    
    // Create a Car object and set its make, model, and year
    Car myCar = new Car("Toyota", "Camry", 2020);
    
    // Display information about the car
    myCar.displayCarInfo();
    
    // Change the make of the car using the setMake() method
    myCar.setMake("Honda");
    
    // Display the updated information about the car
    myCar.displayCarInfo();
}
}

Output:

Make: Toyota
Model: Camry
Year: 2020
Make: Honda
Model: Camry
Year: 2020

5.Singleton Class:

In Java, a Singleton class is a class that can have only one object (an instance of the class) at a time. The class provides a global point of access to that instance, which can be accessed from anywhere within the application.

Purpose:

  1. To ensure that only one instance of the class exists in the JVM.
  2. To provide a global point of access to the object.
  3. To control the creation and initialization of the object.
  4. To restrict the number of instances that can be created.
  5. To provide a way to access the instance of the class without creating a new object every time.

Properties:

  1. Private Constructor: A singleton class must have a private constructor to restrict the creation of objects from outside of the class.
  2. Private static instance variable: A singleton class must have a private static instance variable which holds the only instance of the class.
  3. Public static method: A singleton class must have a public static method to access the instance of the class. The method is used to return the instance of the class.

ALGORITHM:

Step 1: Declare a private static instance variable of the Singleton class.

Step 2: Declare a private constructor to prevent the creation of multiple instances of the class.

Step 3: Define a public static method to create and return the Singleton instance.

Step 4: Check if the instance is null, and if it is, create a new Singleton instance.

Step 5: Return the Singleton instance.

Step 6: Define a public method to demonstrate the functionality of the Singleton instance.

Step 7: In the main function, create two instances of the Singleton class.

Step 8: Display the memory addresses of the two instances.

Step 9: Demonstrate that both instances refer to the same Singleton object.

Step 10: Call the showMessage() method using one of the Singleton instances.

FileName: Singleton.java

import java.util.*;
public class Singleton {
    
    // Declare a private static instance variable of the Singleton class
    private static Singleton instance;
    
    // Declare a private constructor to prevent the creation of multiple instances of the class
    private Singleton() {}
    
    // Define a public static method to create and return the Singleton instance
    public static Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
    
    // Define a public method to demonstrate the functionality of the Singleton instance
    public void showMessage() {
        System.out.println("Hello World!");
    }
    
    // Main function to test the Singleton class
    public static void main(String[] args) {
        
        // Create two instances of the Singleton class
        Singleton obj1 = Singleton.getInstance();
        Singleton obj2 = Singleton.getInstance();
        
        // Display the memory addresses of the two instances
        System.out.println("Memory address of obj1: " + obj1);
        System.out.println("Memory address of obj2: " + obj2);
        
        // Demonstrate that both instances refer to the same Singleton object
        if (obj1 == obj2) {
            System.out.println("obj1 and obj2 refer to the same Singleton instance.");
        } else {
            System.out.println("obj1 and obj2 refer to different Singleton instances.");
        }
        
        // Call the showMessage() method using one of the Singleton instances
        obj1.showMessage();
    }
}

Output:

Memory address of obj1: Singleton@3af49f1c
Memory address of obj2: Singleton@3af49f1c
obj1 and obj2 refer to the same Singleton instance.
Hello World!

6. POJO Class (Plain Old Java Object):

A POJO (Plain Old Java Object) is a Java class that encapsulates only fields with getters and setters methods. The POJO class does not depend on any external framework, making it simple, easy to understand, and reusable.

Purpose:

  1. Standardized way to represent data objects
  2. Easily share data between different layers of an application
  3. Simple and reusable code
  4. Easily maintainable and testable code
  5. Essential component of object-oriented programming practices
  6. Ideal for use in modern software development, particularly in enterprise application development
  7. Enables the creation of applications that are easy to scale

Properties:

  1. Plain and simple Java class.
  2. Encapsulates data using getters and setters.
  3. No external framework dependencies
  4. Serializable

ALGORITHM:
Step 1:
Create a Person class with name, age, and address as its properties.

Step 2: Define default and parameterized constructors for the class.

Step 3: Define getter and setter methods for the properties.

Step 4: In the main function:

Step 4.1: Create an instance of the Person class using the default constructor.

Step 4.2: Set the properties of the person object using the setter methods.

Step 4.3: Retrieve and display the properties of the person object using the getter methods.

Step 4.4: Create another instance of the Person class using the parameterized constructor.

Step 4.5: Retrieve and display the properties of the person object using the getter methods.

FileName: Person.java

import java.util.*;
public class Person {
// Properties of the class
private String name;
private int age;
private String address;
// Default constructor
public Person() {
    // Empty constructor
}


// Parameterized constructor
public Person(String name, int age, String address) {
    this.name = name;
    this.age = age;
    this.address = address;
}


// Getter and setter methods for the properties
public String getName() {
    return name;
}


public void setName(String name) {
    this.name = name;
}


public int getAge() {
    return age;
}


public void setAge(int age) {
    this.age = age;
}


public String getAddress() {
    return address;
}


public void setAddress(String address) {
    this.address = address;
}


// Main function to demonstrate usage of POJO class
public static void main(String[] args) {
    // Create an instance of the Person class using the default constructor
    Person person1 = new Person();


    // Set properties using setter methods
    person1.setName("Chandu");
    person1.setAge(20);
    person1.setAddress("123 Hyderabad, Anytown India");


    // Retrieve and display properties using getter methods
    System.out.println("Name: " + person1.getName());
    System.out.println("Age: " + person1.getAge());
    System.out.println("Address: " + person1.getAddress());


    // Create another instance of the Person class using the parameterized constructor
    Person person2 = new Person("Rahul", 22, "456 Medak St, Anycity Telangana");


    // Retrieve and display properties using getter methods
    System.out.println("Name: " + person2.getName());
    System.out.println("Age: " + person2.getAge());
    System.out.println("Address: " + person2.getAddress());
}
}

Output:

Name: Chandu
Age: 20
Address: 123 Hyderabad, Anytown India
Name: Rahul
Age: 22
Address: 456 Medak St, Anycity Telangana

7.Inner Class (Non-static Nested Class):

In Java, an inner class is a class that is defined inside another class. It can be either static or non-static. A non-static inner class is also known as a nested class.

Purpose:

  1. Encapsulation of related functionality within a single class
  2. Improved code readability by grouping classes together
  3. Access to private members of outer class for implementing certain design patterns
  4. Event handling in Java GUIs

Properties:

  1. Scope: Inner classes have access to all members of outer class, including private members
  2. Instantiation: Inner class instances can only be created within an instance of the outer class
  3. Name: Inner class name is typically outer class name followed by dot and inner class name
  4. Modifiers: Inner classes can have the same modifiers as any other class, such as public, private, protected, and static
  5. Relationship to outer class: Non-static inner classes have an implicit reference to their outer class, which can be accessed using OuterClassName.this syntax.

ALGORITHM:

Step 1: Define the OuterClass with a private member variable x and a constructor to set its value.

Step 2: Define the non-static InnerClass inside OuterClass with a private member variable y and a constructor to set its value.

Step 3: Define a method sum() inside InnerClass that returns the sum of x and y.

Step 4: In the main method, create an instance of OuterClass and use it to create an instance of InnerClass.

Step 5: Call the sum() method of InnerClass to get the sum of x and y.

Step 6: Print the result.

FileName: OuterClass.java

import java.util.*;
public class OuterClass {
    
    private int x; // private member variable of outer class
    
    // constructor of outer class
    public OuterClass(int x) {
        this.x = x;
    }
    
    // non-static inner class definition
    public class InnerClass {
        
        private int y; // private member variable of inner class
        
        // constructor of inner class
        public InnerClass(int y) {
            this.y = y;
        }
        
        // method of inner class that uses both inner and outer class members
        public int sum() {
            return x + y;
        }
    }
    
    // main method to create instances of outer and inner classes
    public static void main(String[] args) {
        
        // create instance of outer class
        OuterClass outer = new OuterClass(10);
        
        // create instance of inner class using outer class instance
        OuterClass.InnerClass inner = outer.new InnerClass(20);
        
        // call sum method of inner class to use both outer and inner class members
        int result = inner.sum();
        
        // print result
        System.out.println("Sum of x and y is: " + result);
    }
}

Output:

Sum of x and y is: 30