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

Java Viva Questions and Answers

Question: Explain Java programming language.

Answer: It is a high-level programming language. This programming language is based on the principles of object-oriented programming. Large-scale applications can be developed by using this programming language. Also called the object-oriented programming language. It is platform independent language. In this modern software era, the Java programming language is the backbone of millions of software applications. Java is used in many real-world Java applications, including technologies and tools. This Java programming language has become the backbone for developing many applications. In areas like embedded systems and in enterprise solutions, this Java has made its mark. Almost three billion devices, irrespective of their operating systems like Android, UNIX, Mac OS, and Windows, use Java for development, according to Oracle.

Question: Explain some of the uses of Java programming language.

Answer: For most of the back-end development projects, this Java programming language is used as the server-side language. In these back-end development projects involving android development and also those involving big data, we use Java. In mobile computing, desktop computing and in numerical computing, Java is the most commonly used programming language. In game consoles, scientific supercomputers, cell phones, data centres and many other devices, Java is used. After C and python programming languages, Java is one of the third most popular programming languages in the world. Java is used widely because of its reliability and ease of use. For constructing applications on laptops, Java is used.

Question: Explain how Java is used in web-based programmes.

Answer:  Java is also known as a server-side programming language. So, in Apache Hadoop, Hibernate, Spring and many others, it is often used for constructing web applications. Famous websites like LinkedIn, Amazon and many others use Java.

Question: Why Java programming language is known as platform independent language?

Answer: This programming language is developed in such a way that it does not depend on any hardware and also on software too. Java is known as platform independent language because of the fact that the compiler compiles the code. And this compiled code is then converted into platform-independent byte code. This code now runs on multiple systems. That's the reason Java is known as "write once run anywhere". For the machine to run this byte code, there is a condition that the machine should have a runtime environment (JRE) installed in it.

Question: Why is Java not a pure object-oriented language?

Answer: Java is not a pure object-oriented language because Java programming language uses primitive data types such as int, float, char, Boolean, short, long and double. Simply we can say that Java has direct access to primitive data types. These primitive data types do not belong to the integer classes directly. Primitive data types could be made as objects like strings by the developers. But the thing is, primitive data types such as float as int are much faster than the object. The developers kept primitive types in their language in order to achieve faster execution. Java is known as a 98% object-oriented language but not a pure object-oriented programming language. Because of the reason Java supports these primitive data types, it does not know as a pure object-oriented language. The reason is in the Java programming language, and everything will be underclasses.

Question: Why is this Java programming language highly suitable for mobile applications?

Answer: As Java is a powerful programming language and also a versatile programming language, it plays an important role in mobile development. This Java can be used for developing a wide range of mobile applications. Android Studio, which is a must for developing mobile applications, is developed by using Java and also it is the official integrated development environment (IDE) for the android platform. This Android Studio is based on IntelliJ IDEA, and this is written in Java and designed in a way to achieve maximum productivity with its powerful code editor. From memory leaks, this Java programming language safeguards the native code. In android development, this versatile programming language is used to compile different functionalities in each platform.

Question: Explain how Java is used in IoT.

Answer: For IoT – (Internet of Things) device development, most developers prefer Java as the best programming language. The main reason here to use it is because this programming language is platform agnostic. We create code only once, and this code operates on a wide variety of devices by reducing the overall workload for the programmers.

Question: Explain the differences between Java programming language and C++.

Answer:

  • One of the main differences between Java and C++ programming languages is that Java is both compiled and interpreted programming language. In contrast, C++ is the only compiled language.
  • If the Java program is once written, it can be run anywhere. Simply, we can say Java is a platform-independent language and also a machine-independent programming language. And Java can be compiled on every platform. In comparison, the C++ program can run only on the machine on which its compilation is done.
  • C++ programming language requires manual memory management, and Java programming language memory management is system controlled.
  • For system programming, mainly C++ language is used. And Java is widely used for application programming. Mostly, the Java programming language is widely used in Windows-based, mobile applications, in web-based applications.
  • Java does not support the goto statement in it. In comparison, C++ supports goto statements to use in the programs.
  • Java does not support operator overloading. But C++ programming language supports operator overloading.
  • Multiple inheritance is supported in C++. Java does not support multiple inheritance. But there is another way to achieve multiple inheritance in Java by using interfaces.
  • Call by value and call by reference were both supported by the C++ programming language. Whereas Java does not support the call by reference, and it only supports the call by value in its programs.
  • Documentation comment is not supported by the C++ programming language. In contrast, Java programming language supports documentation comments. And these documentation comments are used to create documentation for Java source code.
  • Default arguments were supported by the C++ programming language. But Java does not support default arguments.
  • Header files were not supported by the Java programming language. But C++ supports header files.
  • The virtual keyword will not be there in Java. In C++ programming language, we use virtual keywords in the programs.
  • In a Java programming language, we have a garbage collector. But in C++, we do not have a garbage collector.
  • Java does not support pointers in its programs. Whereas in C++ programming language, we will have pointers, and we use the pointers when we are writing the program.
  • We do not have global variables in the Java programming language. In C++, we will have global variables in its programs.
  • Template class will be there in C++. But in the Java programming language, we do not have a template class in its programs.
  • One of the other main differences between Java and C++ programming languages is in Java, and we will have packages and interfaces. But in the C++ programming language, we do not have packages and interfaces.
  • We do not have API in C++. We have API in the Java programming language.
  • There will be a pretty consistent between primitive data types and object types in C++ programming language. But in the Java programming language, semantics differs between object types and primitive data types.
  • Both namespace scopes and global scopes were supported by C++. Java does not support global scope in its programs.
  • When it comes to access control and object protection, a flexible model with constant protection is available in C++ programming language. Java encourages weak encapsulation, and in the Java programming language, the model is cumbersome.

Question: Explain the similarities between Java and C++.

Answer:

The similarities between Java and C++ programming languages.

  • With both C++ and Java programming languages, we have vast areas of applications.
    Like using C++ programming languages, MYSQL is written, and C++ is mostly and also majorly used in game development. Popular applications like Adobe Premiere, Illustrator and a few others were scripted by using C++ programming language only. High-performance image processing is done by using this C++. Also widely used in many advanced types of medical equipment. Cluster data processing, File system and also Google chromium browser file all are in using the C++ programming language. Large software is developed by using this programming language, and it is suitable for it.
    As Java is a versatile programming language and also a powerful programming language, it is used in a wide variety of software applications in most software fields all over the world. Mainly Java is used in mobile and also in android application development. Java is also used in network applications and Web app development. For running large enterprise software, Java enterprise Edition provides an API and also a runtime environment. Desktop GUI applications were developed using the Java programming language. Applications developed by Java programming language embedded in the highly used technologies like disk players, TV and also mainly in SIM cards which we use in mobile phones.
  • In both programming languages, abstraction is there.
  • In both C++ and Java programming languages, encapsulation is there.
  • Single inheritance will be there in both languages. But when it comes to multiple inheritance it will be there in C++ but not in the Java programming language, but it can be achieved by some other method in Java, but not directly.
  • In both programming languages, polymorphism is possible.
  • Static binding is there in both C++ and also in Java.
  • Dynamic binding, too, is there both the programming languages.
  • For both programming languages, the syntax is almost similar.
  • Comments like single-line comments and also multiple-line comments are written in the same in both programming languages.
  • Conditional statements like if statement, if-else statement, nested if, else if, and switch statements are similar in both programming languages.
  • Loops like the while loop and for loop (Simple for loop and nested for loop) are similar in both the C++ programming language and also in the Java programming language.
  • Operators like relational operators and arithmetic operators are the same in both programming languages.
  • In both C++ and in Java programming languages, the execution of the programs written starts from the main function only. (The only difference is main function declaration is different in C++ and Java, but the name is the same.)
  • In both programming languages, the statements written in the program will end with a semicolon only. (;)
  •  Primitive data types like int, float, double, long, short, Boolean, and char are similar in both C++ and Java programming languages.
    But the Boolean value in C++ is called bool, and in the Java programming language, it is called a Boolean value.
  • Keywords like public, private and protected are the same in both programming languages. And those keywords are known as access specifiers.
  • Other most used keywords like static, return, new, double, break, continue, and char are similar in both C++ and Java programming languages.
  •  One of the important concepts of multi-threading is supported by both Java and C++ programming languages.
    These programming languages allow us to execute multiple threads concurrently, and by this execution, one can achieve multitasking.

 Question: Explain the difference between stack memory and heap memory in Java.

Answer:

Stack Memory: As the name indicates, static memory is the memory in a Java programming language which is used for static memory allocation. And also, this static memory is used for the execution of the threads. For a class, when an object has been created, the reference of the object will contain in stack memory, and this object will always be stored in heap memory. For each object created separate stack will be get created by this stack memory. Automatically stack allocation will be done by the operating system which we are using when a thread is created. It is not used by all parts of the application, and this stack memory is used only by one thread of execution. For each thread, at run time, this stack memory will be get allocated, and this stack memory is a physical space in Random Access Memory (RAM). This stack memory follows LIFO (Last In First Out) for accessing the memory. Simply we can say that memory management follows LIFO (Last In First Out). To the owner thread, only the variables are visible in this stack memory. This stack memory is mainly used to store the local variables and to store the order of method execution. Memory allocation in this stack memory is continuous allocation. When the thread is created, this memory will be get created. It was accessible globally. A separate stack for each thread will be created by Java Virtual Machine (JVM). We cannot alter the allocated memory once it is done. This stack memory is not flexible like heap memory. Allocation and deallocation are faster in this stack memory. Faster access will be there in this memory type. Memory size is similar in this memory. Another important thing is we can increase the size of the stack by using the JVM option -Xss. Java.lang.StackOverFlowError will be get thrown automatically whenever the stack size is greater than the limit it allocated. So to avoid this error, only we increase the size of the stack by using the JVM option -Xss. The advantage of using this memory is the cost will be less when compared to heap memory, and it is affordable. But the implementation of the stack memory is hard. Using this stack memory, we can say it is threaded safe because for every thread created, there will be its own stack for every thread.

Heap Memory: Heap memory is also known as dynamic memory; it is the area memory in which objects get stored. Memory block allocation and deallocation are not done in a fixed pattern. Simply, we can say the allocation of memory is done randomly. Implementation of heap memory is easy, but the cost of this memory is more when compared to stack memory. This memory is shared among all threads. Heap memory will be created when the Java Virtual Machine starts running. As long as the application is running, the heap which is created is shared between the threads of the objects. For local stack memory, heap memory is the alternative stack memory. In heap memory, automatically, local variables are allocated when a function is called. As the function exits, deallocation of the local variables is done automatically. The size of the heap memory is larger when compared to stack memory. Allocation and deallocation are slower. Also, the access is slower than stack memory. As we can alter the memory, this heap memory is flexible. JRE (Java Runtime Environment) classes and also objects are stored in this memory. As the alternative indicates, this memory does not follow any order. The memory allocation is done dynamically. -Xmx and -Xms JVM options are used to increase or decrease the size of the heap memory. In stack memory, we can increase the size of the stack, but here we can increase or decrease the size of the heap memory. Visible to all threads. Java.lang.OutOfMemoryError will be thrown by the Java Virtual machine, and this exception arises when Java Virtual Machine is unable to create a new native method. Allocation and deallocation are done by the programmer in heap memory. As stack memory, this heap memory is not thread-safe. The code which is properly synchronized is required.

Question: Why does Java not make use of pointers as they are used in C and C++ programming languages?

Answer: As a beginner programmer, it is not that good and safe to use pointers. Because the reason is they are quite complicated, and their usage of them in the code makes the code complicated and challenging to the programmer. The main of the Java programming language is to make code simple but not complicated. Potential errors can be caused by using these pointers utilization in the program. If we use pointers in the program, the user can directly access the memory with the help of these pointers. So, when we use pointers in the program, we have to compromise the security of the access, and here security issues arise because of the usage of pointers. To reduce the usage of memory spaces, the Java programming language does not make use of the concept of this pointer in its programs, and the reason is these pointers take more time at the run time and also occupy more memory space at the run time. We can say that overall, this Java programming language does not have and also it does not support the concept of the pointer. The usage of pointers in the programs makes robustness and makes the programming language hard to understand and makes it complex too. So, this Java uses the idea of references in it instead of using pointers in its language. So, in the Java programming language, these pointers are called references. And the use of these references is much more than using of pointers. Pointer has the null value, but the references do not.

Question: Explain instance variables in Java.

Answer: Instance Variables: Instance variables can be said as non-static variables in Java. These instance variables are defined in a class but outside of any methods, blocks or also in constructors.

As we know that whenever a class is defined, its instance will be created. And that instance is known as an object. We say a class is instantiated if and only if its object (its instance) is created. And also, these instance variables are accessible to all the methods, blocks, and to constructors.

In the most simplified way, we can see that the instance variables are the variables outside of any method, but they are a must in a class.

We can declare instance variables by using different types of access modifiers available in a Java programming language like private, public, default and protected.

When an object of the class is created or at the time of class loading, initialization of the instance variable is done.

 Let us take an example program to understand the instance variables.

public class AtheleteGame {
public String athleteFullName;
public double athleteSpeedPerHour;
public int athleteAge;
public int athleteIdNumber;


public AthleteGame (name, speed, age, id) {
this.athleteFullName = name;
this.athleteSpeedPerHour = speed;
this.athleteAge = age;
this.athleteIdNumber = id;
}
public void athleteRuns() {
double speed = 200;
String name = “Usha”;
int age = 30;
int id = 234;
system.out.println(“Athlete Name is” + name + “.”);
system.out.println(“Athlete speed is”+ speed + “km/hr in the given target”);
system.out.println(“Athlete age is” + age + “currently”);
system.out.println(“Athlete id is” + id + “in the group);
}
}

 In the program athleteFullName, athleteSpeedPerHour, athleteAge, and, athleteIdNumber are the instance variables.

Question: Explain the default values of instances and variables in the Java programming language.

Answer:

  • For variables, there will be no default values.
  • In Java, we have to initialize values for them before using variables.
  • If we do not initialize variables and we use them in the program, they will throw a compilation error when we execute the program.
  • When it comes to instances in the Java programming language, the default constructor in the program will assign the default value for the instance when we create an object for it.
  • Depending upon the data type, the default value will be get assigned.
  • The null value will be get assigned if it is a reference.
  • The “zero” will be assigned if the instance variable is numeric type.
  • "False" will be get assigned if it is a Boolean type.

 Question: Can we overload static methods?

Answer: With different input parameters and with the same name, we can overload the static method in the Java programming language. So, the answer is yes, and we can overload the static methods. There can be two or more static methods in the program.

Question: Can we override the static methods in a Java programming language?

Answer: The answer is no; we cannot override the static methods in the Java programming language.

The reason is the run time polymorphism will not take place in the case when the declaration of static methods having the same signature is made in the subclass.

As we know that dynamic polymorphism, which is also called overriding, will occur at the runtime.

And these static methods are looked up at the compile time statically. So, that is the reason that we cannot override the static methods in the Java programming language.

Question: Explain shallow and deep copy in the Java programming language.

Answer: Shallow copy and deep copy are some of the methods in several methods which are used to copy the object’s data.

Shallow Copy: This method will create a new reference. And points to the same object which is already written.

Deep Copy: Unlike the shallow copy in this method, we create a new object directly. But, in shallow copy, we create a new reference instead of a new object. Here, in deep, copy the old object value to the created new object.

Question: Explain the main objective of garbage collection in the Java programming language.

Answer: The memory space which is occupied by the objects which are unreachable and unnecessary gets freed up by this garbage collector. This process is done by the garbage collector at the time of execution by deleting unreachable and unnecessary objects.

Question: Explain static methods in the Java programming language.

Answer: If we declare any method using the keyword static, then the method is called a static method.This static method belongs to the class of the program. For the static methods, when the class is loaded, it gets memory. But this method does not belong to the object of the class. For static methods, they have access to the static variables. If we take the example of the static method, the main () method is the most common example. We can call these static methods without creating an object in the class because they can be directly called when by the classes in the program.

Question: Explain static classes in the Java programming language.

Answer: The important thing about the static classes is in the Java programming language, the classes cannot be static as static variables and static methods. But if the class is the inner class, then it can be a static class. The static class will work exactly like the static members of the class if it is the static inner class.

Question: What is data encapsulation?

Answer: It is one of the object-oriented programming concepts. It is the concept of hiding data attributes as we know that in this Java object-oriented programming language, these data and code are getting associated with the objects of the classes. Also, encapsulation can be defined as the process which combines code and data into a single unit. To implement this encapsulation, Java uses the concept of class.

Question: Explain abstraction in the Java programming language.

Answer: It is also one of the object-oriented programming concepts in the Java programming language. This abstraction does not show the actual things to the end user mainly. The main objective of this concept in object-oriented languages is to hide the details which are internal, and it shows only essential functionality to the user. And shows only the things that the user needs to know.