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

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

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

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()

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 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 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

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 concurrency interview questions 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 Coding Interview Questions in 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 Creation of Multi-Thread 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

Tree Implementation in Java

Introduction to Tree

A non-linear, hierarchical data structure called a "tree" is made up of a number of nodes, each of which contains a values and a sequence of pointers to other nodes.

The above data structure is a particular way to set up data storage and arrangement in the computer so that it can be used much more efficiently. It is made up of basic nodes, sub-nodes, and a center node that are all interconnected by edges. The roots, branches, and leaves of a tree data structure are all linked to one another.

Properties of Tree Data Structure

  • Non-Linear Nature
    In other words, a tree does not store its data properly or in a systematic way. Rather, they are grouped in a hierarchical system with several layers. Thus, the tree is regarded as a non-linear data structure as a result.
  • Recursive Nature
    The word "tree" is sometimes used to describe a recursive data structure. Because the distinguishing node in a tree data structure is referred to as a root node, a tree can be described as recursive data structure. The roots of subtrees of the trees are linked from the root node. The left subtree can be divided further into the three subtrees represented in various types. Recursion is the mathematical concept of self-similar reduction. As a result, many implementations use the tree data structure's recursive characteristic.
  • Number of Edges
    The link that connects two nodes is referred to as an edge. A tree will have (N-1) edges if it contains N nodes. There is only one method to move from every node to another node in the tree.
  • Depth of the node
    The distance from the root to a node is referred to as the node's depth. The path gains one unit of length for each edge. As a result, it may alternatively be described as the quantity of edges along the route leading from the tree's root to each node.
  • Height of node
    The height of a node can be defined as the length of the longest path from the node to a leaf node of the tree.
  • Height of Tree
    The distance along the longest path from a tree's root to one of its leaf nodes determines the size of the tree.
  • Degree of node
    The level of the node or the degree is the total number of subtrees that are connected to that node. A leaf node must have a degree of 0. The highest degree achieved by a node from all other nodes in the tree is the degree of the tree.

Types of Tree data structures

The following are the types of trees in java

  • General Tree
  • Binary Tree
  • Binary Search Tree
  • B- Tree

General Tree

One of the different kinds of tree data structures is the general tree. A node in the general tree can have a capacity of n nodes or Nil nodes. There are no restrictions placed on the degree of the node (the total count of nodes which a node can hold). A root node is the first node in a basic tree. Subtrees are the parent node's grandchildren.

A general tree could include n number of subtrees. The subtrees in the general tree are not organized since the subtree's nodes can not be arranged.

The downstream edges of any non-empty tree are linked to the nodes referred to as child nodes. Level 0 denotes to the base node. Sibling nodes are those who share the same parent node.

Binary Tree

Binary trees are trees in which every node (parent) has a maximum of two children (left and right). The root node is the highest node in the tree. The information and reference (address) of the left and right child nodes are represented in each node of a binary tree.

A binary tree's height is determined by how many connections are there between its root and its longest (deepest) leaf. The height is zero if the tree is empty. The letter h stands for the node's height.

The procedure below can be used to determine the number of nodes and leaves.

  • The most leaf nodes a binary tree can have is denoted by "2h".
  • The most nodes a binary tree can have or contain are "2h+1-1".

Binary Search Tree

A binary search tree is a binary tree where every other node has an Unique key (and an associated value) and fits with the condition that no node's key must be both greater than and smaller than all other nodes' keys in both the left and right subtrees of that node.

Properties

There are certain rules while constructing a binary search tree. They are as following:

  • A node's left subtree only has nodes with values lower than the node itself.
  • Those nodes with values higher than the node's value are found in the right subtree of the node.
  • A binary search tree needs to be represented in both the left and right subtrees.

B-Tree

A specific m-way tree that is frequently used for disc access termed as the B Tree. A B-Tree of type m can contain m children and at most m-1 nodes. One of the primary advantages of implementing a B tree is its capable of storing many keys in a single point and huge key values while having a consistent small tree height

Properties

  • The height of each leaf node is the similar.
  • The phrase minimal degree "t" implies a B-Tree. The size of a file system determines the value of t.
  • All nodes must have t-1 keys, with the exception of root. The root may have at least one key.
  • For most 2*t - 1 values may be present in any node, along with the root.
  • A node has as many children as its amount of keys plus one.
  • A node's keys are arranged in ascending order. All keys inside the range among both k1 and k2 are contained in the child between k1 and k2.
  • In contradiction to Binary Search Tree, the B-Tree expands and decreases from the base. Binary search trees can both expand and diminish .
  •  

Implementation of General Tree

Rules to be followed

  • A tree is a node. The tree's root is situated at that node.
  • We can establish a new tree where t will be the parent of the nodes t1, t2,..., tk if r is a node and S1, S2,..., Sk are subtrees with roots t1, t2,..., tk. S1, S2,..., and Sk are subtrees of the root of the new tree, where r is the root. The nodes t1, t2,..., and tk are referred to as the node r's children.
  • The empty tree can be helpful at times. There are no nodes in this tree.

Let us understand the implementation of a general tree with an example program

// Java program to do level order traversal
// of a generic tree
import java.util.*;


class Demo111
{


// Representation of a node in n-ary tree
static class Node
{
int key;
Vector<Node >child = new Vector<>();
};


// Utility function to create a new tree node
static Node newNode(int key)
{
Node tem = new Node();
temp.key = key;
return tem;
}


// Prints the n-ary tree level wise
static void LOT(Node root)
{
if (root == null)
return;


// Standard level order traversal code
// using queue
Queue<Node > rk = new LinkedList<>(); // Create a queue
rk.add(root); // Enqueue root
while (!rk.isEmpty())
{
int n = rk.size();


// If this node has children
while (n > 0)
{
// Dequeue an item from queue
// and print it
Node p =rk.peek();
rk.remove();
System.out.print(p.key + " ");


// Enqueue all children of
// the dequeued item
for (int i = 0; i < p.child.size(); i++)
rk.add(p.child.get(i));
n--;
}

// Print new line between two levels
System.out.println();
}
}


// Driver Code
public static void main(String[] args)
{


Node ob = newNode(11);
(ob.child).add(newNode(3));
(ob.child).add(newNode(37));
(ob.child).add(newNode(51));
(ob.child).add(newNode(111));
(ob.child.get(0).child).add(newNode(74));
(ob.child.get(0).child).add(newNode(83));
(ob.child.get(2).child).add(newNode(2));
(ob.child.get(3).child).add(newNode(9));
(ob.child.get(3).child).add(newNode(7));
(ob.child.get(3).child).add(newNode(6));


System.out.println("Level order traversal " +"Before Mirroring ");
LOT (root);
}
}

Output

Level order traversal of the general tree
11
3 37 51 111
 74 83 2 9 7 6

The above program depicts of how the general tree is implemented in Java.

Initially a root node of the tree is created. Then the children of that tree which implies the child nodes of the tree are created. The nodes corresponding to the left part of the entire tree is called as left-subtree. The nodes corresponding to the right part of the entire tree is called as right-subtree.

In the of a general tree, child nodes are stored in a vector. As a result, we arrange all of the vector's components.

Implementation of Binary Tree

Types of Implementations in Binary Tree

Pre-Order Traversal: Root - Left Child - Right Child is the order of traversing. This indicates that the root node is travelled through initially, followed by its left child or the left sub-tree and then its right child or the right-subtree.

In-Order Traversal: Left child, root, and right child make up the traversal. The left child, its root node, and subsequently the right child is traversed in that order.

Post-Order Traversal: Left child - right child - root is the traversing order. It indicates that the left child is followed by the right child and then the root node.

Let us understand the implementation of a binary tree with an example program

// Binary Tree in Java
// Creation of Node
class Node111 {
  int key;
  Node left, right;


  public Node(int item) {
  key = item;
  left = right = null;
  }
}


class BT {
  Node root;


  BT(int key) {
  root = new Node(key);
  }


  BT() {
  root = null;
  }


  // In-order Traversal
  public void traverseInOrder(Node node) {
  if (node != null) {
    traverseInOrder(node.left);
    System.out.print(" " + node.key);
    traverseInOrder(node.right);
  }
  }


  // Post-order Traversal
  public void traversePostOrder(Node node) {
  if (node != null) {
    traversePostOrder(node.left);
    traversePostOrder(node.right);
    System.out.print(" " + node.key);
  }
  }


  //Pre-order Traversal
  public void traversePreOrder(Node node) {
  if (node != null) {
    System.out.print(" " + node.key);
    traversePreOrder(node.left);
    traversePreOrder(node.right);
  }
  }


  public static void main(String[] args) {
  BinaryTree tr = new BinaryTree();


  tr.root = new Node(11);
  tr.root.left = new Node(12);
  tr.root.right = new Node(13);
  tr.root.left.left = new Node(14);


  System.out.print("Pre order Traversing: ");
  tr.traversePreOrder(tree.root);
  System.out.print("\nIn order Traversing: ");
  tr.traverseInOrder(tree.root);
  System.out.print("\nPost order Traversing: ");
  tr.traversePostOrder(tree.root);
  }
}

Output

Pre order Traversing: 1 2 4 3
In order Traversing:  4 2 13
Post order Traversing:  4 2 3 1

Summary of Binary Tree

A topological data structure is a tree. Trees are mostly used for insert/delete tasks, modest access, and keeping data structure. A binary tree is a special type of tree where each node has a maximum of two offspring.

Applications

  • Expression Trees, a binary tree implementation, are employed in interpreters.
  • Techniques for lossless compression employ Huffman coding trees.
  • A further binary tree implementation that searches maximum or minimum in O(1) time complexity is priority queue.

Implementation of Binary Search Tree

The Binary Search Tree is implemented in many ways using many operations. They are discussed as below:

  • Insertion
  • Deletion

Insertion

  • If the value of the new node is less than the root node then, it will be inserted to the left subtree.
  • If the value of the new node is greater than root node then, it will be inserted to the right subtree.

Deletion

  • A binary search tree's given node could be removed using the delete operation. But, we have to remove a node from a binary search tree in a manner it doesn't contradict that criteria.
  • If the node to be deleted is a leaf node, in this case, replace the leaf node with the NULL and simple free the allocated space.
  • If the node that has to be deleted has only one child, try replacing the node in this instance with its child and then remove the child node because it currently consists the value that needs to be deleted. Consider replacing it with Zero values to release the space that was allotted.
  • If the node that has to be deleted has two children, then it is a bit complex situation. Right till the node value is inserted on the tree leaf, the node that has to removed is successively replaced by its in-order successor or predecessor. Update the node with Zero values and release the space after the process.

The below program shall depict the implementation of binary search tree using the above discussed operations.

public class BST {  
  
    //Representation of binary tree structure
    public static class Node{  
        int data;  
        Node left;  
        Node right;  
  
        public Node(int data){  
            //Assign data to the new node, set left and right children to null  
            this.data = data;  
            this.left = null;  
            this.right = null;  
        }  
      }  
  
      //Representation if binary tree structure  
      public Node root;  
  
      public BinarySearchTree(){  
          root = null;  
      }  
  
      //insert() method shall help in adding the node
      public void insert(int data) {  
          //Creation a new node  
          Node ob = new Node(data);  
  
          //Verifying if tree is empty  
          if(root == null){  
              root = ob;  
              return;  
            }  
          else {  
              //current node points to root node of the tree  
              Node current = root, parent = null;  
  
              while(true) {  
                  parent = current;  
  
                  // Node would be introduced towards the left of the current node if value is less than current value of tree  
                  if(data < current.data) {  
                      current = current.left;  
                      if(current == null) {  
                          parent.left = ob;  
                          return;  
                      }  
                  }  
                  //The node will be inserted towards the right side of the tree if the value is greater than current value  
                  else {  
                      current = current.right;  
                      if(current == null) {  
                          parent.right = ob;  
                          return;  
                      }  
                  }  
              }  
          }  
      }  
  
      //minNode() method is used to find the node with minimum value
      public Node minNode(Node root) {  
          if (root.left != null)  
              return minNode(root.left);  
          else  
              return root;  
      }  
  
      //deleteNode() method is used to remove the node from the given binary tree
      public Node deleteNode(Node node, int value) {  
          if(node == null){  
              return null;  
           }  
          else {  
              //must search towards the left of the tree if the value is lee than the given data
              if(value < node.data)  
                  node.left = deleteNode(node.left, value);  
  
              //search towards  right side of the node data if the value is greater than node data 
              else if(value > node.data)  
                  node.right = deleteNode(node.right, value);  
  
              //If the searching value is found then there is no need to search
 {  
                  //The node meant to be deleted has no child then consider it null  
                  if(node.left == null && node.right == null)  
                      node = null;  
  
                  //The node which is meant to be deleted has only right child  
                  else if(node.left == null) {  
                      node = node.right;  
                  }  
  
                  //The node which is meant to be deleted has only left child  
                  else if(node.right == null) {  
                      node = node.left;  
                  }  
  
                  //The node which is meant to be deleted has two children nodes 
                  else {  
                      //then find the minimum node from right subtree  
                      Node tem = minNode(node.right);  
                      //Exchange the data between node and temp  
                      node.data = tem.data;  
                      //Delete the node duplicate node from right subtree  
                      node.right = deleteNode(node.right, tem.data);  
                  }  
              }  
              return node;  
          }  
      }  
  
      //inorder() will perform inorder traversal on binary search tree  
      public void inorderTraversal(Node node) {  
  
          //Check whether tree is empty  
          if(root == null){  
              System.out.println("Tree is empty");  
              return;  
           }  
          else {  
  
              if(node.left!= null)  
                  inorderTraversal(node.left);  
              System.out.print(node.data + " ");  
              if(node.right!= null)  
                  inorderTraversal(node.right);  
  
          }  
      }  
  
      public static void main(String[] args) {  
  
          BinarySearchTree rk = new BinarySearchTree();  
          //Add nodes to the binary tree  
          rk.insert(10);  
          rk.insert(20);  
          rk.insert(30);  
          rk.insert(40);  
          rk.insert(50);  
          rk.insert(60);  
  
          System.out.println("Binary search tree after inserting the values:");  
          //Displays the binary tree  
          rk.inorderTraversal(rk.root);  
  
          Node deletedNode = null;  
          //Deletes node 60 which has no child  
          deletedNode = rk.deleteNode(bt.root, 60);  
          System.out.println("\nBinary search tree after deleting node 90:");  
          rk.inorderTraversal(bt.root);  
  
          //Deletes node 30  
          deletedNode = rk.deleteNode(bt.root, 30);  
          System.out.println("\nBinary search tree after deleting node 30:");  
          rk.inorderTraversal(rk.root);  
  
          //Deletes node 50 
          deletedNode = rk.deleteNode(bt.root, 50);  
          System.out.println("\nBinary search tree after deleting node 50:");  
          rk.inorderTraversal(rk.root);  
      }  
}  

Output

Binary search tree after inserting the values:
10 20 30 40 50 60 
Binary search tree after deletion node 60:
10 20 30 40 50 
Binary search tree after deleting node 30:
10 20 40 50  
Binary search tree after deleting node 50:
10 20 40 

Implementation of B-Tree

The operations for implementing the B-Tree are

  • Searching
  • Traversal

Searching

The search process is comparable to that of a binary search tree. Let "m" be the searchable key. Iteratively, we move across the tree starting at the root. If the node holds the key for any visited non-leaf nodes, we just return the node. If not, we go back to the node's corresponding child (the child that comes before the first greater key). It provides NULL if we approach a leaf node but can't find "m" there.

Traversal

Traversal is comparable to in-order binary tree traversal. Iteratively printing the left child after starting with the first one, we continue in the same manner with the values and subsequent children. Iteratively display the rightmost child at the conclusion.

The below program shall depict the implementation of B-Tree with the suitable operations.

// Searching a key on a B-tree in Java 


public class BTree {


  private int T;


  // Node creation
  public class Node {
    int n;
    int key[] = new int[2 * T - 1];
    Node child[] = new Node[2 * T];
    boolean leaf = true;


    public int Find(int k) {
      for (int i = 0; i < this.n; i++) {
        if (this.key[i] == k) {
          return i;
        }
      }
      return -1;
    };
  }


  public BTree(int t) {
    T = t;
    root = new Node();
    root.n = 0;
    root.leaf = true;
  }


  private Node root;


  // Search key
  private Node Search(Node x, int key) {
    int i = 0;
    if (x == null)
      return x;
    for (i = 0; i < x.n; i++) {
      if (key < x.key[i]) {
        break;
      }
      if (key == x.key[i]) {
        return x;
      }
    }
    if (x.leaf) {
      return null;
    } else {
      return Search(x.child[i], key);
    }
  }


  // Splitting the node
  private void Split(Node x, int pos, Node y) {
    Node z = new Node();
    z.leaf = y.leaf;
    z.n = T - 1;
    for (int j = 0; j < T - 1; j++) {
      z.key[j] = y.key[j + T];
    }
    if (!y.leaf) {
      for (int j = 0; j < T; j++) {
        z.child[j] = y.child[j + T];
      }
    }
    y.n = T - 1;
    for (int j = x.n; j >= pos + 1; j--) {
      x.child[j + 1] = x.child[j];
    }
    x.child[pos + 1] = z;


    for (int j = x.n - 1; j >= pos; j--) {
      x.key[j + 1] = x.key[j];
    }
    x.key[pos] = y.key[T - 1];
    x.n = x.n + 1;
  }


  // Inserting a value
  public void Insert(final int key) {
    Node r = root;
    if (r.n == 2 * T - 1) {
      Node s = new Node();
      root = s;
      s.leaf = false;
      s.n = 0;
      s.child[0] = r;
      Split(s, 0, r);
      insertValue(s, key);
    } else {
      insertValue(r, key);
    }
  }


  // Insert the node
  final private void insertValue(Node x, int k) {


    if (x.leaf) {
      int i = 0;
      for (i = x.n - 1; i >= 0 && k < x.key[i]; i--) {
        x.key[i + 1] = x.key[i];
      }
      x.key[i + 1] = k;
      x.n = x.n + 1;
    } else {
      int i = 0;
      for (i = x.n - 1; i >= 0 && k < x.key[i]; i--) {
      }
      ;
      i++;
      Node tmp = x.child[i];
      if (tmp.n == 2 * T - 1) {
        Split(x, i, tmp);
        if (k > x.key[i]) {
          i++;
        }
      }
      insertValue(x.child[i], k);
    }


  }


  public void Show() {
    Show(root);
  }


  // Display
  private void Show(Node x) {
    assert (x == null);
    for (int i = 0; i < x.n; i++) {
      System.out.print(x.key[i] + " ");
    }
    if (!x.leaf) {
      for (int i = 0; i < x.n + 1; i++) {
        Show(x.child[i]);
      }
    }
  }


  // Check if present
  public boolean Contain(int k) {
    if (this.Search(root, k) != null) {
      return true;
    } else {
      return false;
    }
  }


  public static void main(String[] args) {
    BTree b = new BTree(3);
    b.Insert(8);
    b.Insert(9);
    b.Insert(10);
    b.Insert(11);
    b.Insert(15);
    b.Insert(20);
    b.Insert(17);


    b.Show();


    if (b.Contain(12)) {
      System.out.println("\nfound");
    } else {
      System.out.println("\nnot found");
    }
    ;
  }
}

Output

10 8 9 11 15 17 20 
not found