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 How to run Java program in command prompt How to run Java program in Eclipse 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 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 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 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

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 Python vs Java 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 C vs 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 How to calculate time difference 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 String Tokenizer and Split Method in Java Difference Between BufferedReader and FileReader Difference Between Thread.start() and Thread.run()

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 create thread in Java How to find length of String 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 create custom exception in Java How to import packages in Java How to run applet Program in Java How to take Array Input in Java How to achieve abstraction 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

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 Servlet Tutorial

Java Servlets Tutorial

Java JSP Tutorial

Java JSP Tutorial

Hiberate Tutorial

Hibernate Tutorial

Spring Tutorial

Spring Tutorial

Spring MVC Tutorial

Spring MVC Tutorial

Jenkins Tutorial

Jenkins Tutorial Jenkins java net socket connection time out

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

Misc

List all files in a Directory in Java Nonagonal number in Java Null Pointer Exception in Java Package naming convention in Java Packages Program in java Pangram Program in Java PriorityBlockingQueue Class in Java Race Condition in Java Repdigit Numbers in Java Reserved Keywords 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 program to print matrix in Z form 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 Case Keyword Java Try-Catch Block Java Class KeywordJava concurrency interview questions Java Continue Keyword Java CountDownLatch Java Default Keyword Java Double Keyword Java Editors Java Else Keyword Java Enum Keyword Java Extends keywordJava Finally Keyword Java Font Example of Static import in Java How Many Ways to Create Objects in Java Implementing Queue Using Array in Java Instanceof operator in Java Interchange Diagonal elements in Java Java Arrays Fill Java Char Keyword Convert list to array Java Convert milliseconds to date in Java Copy data/content from one file to another in java CRC Program in Java Creating a Jar file in Java Crown Pattern in Java Difference Between Access Specifiers and Modifiers in Java Difference Between Java and PHP Difference Between replace() and replaceall() in Java Duodecimal in Java Finding middle node of a linked list in Java Group by in Java 8 Hollow Diamond Pattern in Java How annotations work in Java Java Boyer Moore Catalan number in Java Cosmic Superclass in Java Difference between this and super 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 Contextual keywords 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 What are Array strings 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 What is String 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 How to stop execution after a certain time in Java 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 What is string in Java why it's immutable 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 Star Program in 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 What is advance Java? 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 Java Break Keyword 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 Java Enumeration Compile-time Error in Java Java Get Time in UTC Java.sql.Time Format Structure of Java Program Thread Concept in Java Creation of Multi-Thread in Java Enterprise Java Beans POJO in Java Volatile keyword in Java Java Constant Collection Interfaces in Java with Examples Deadlock Prevention and avoidance in Java Java Boolean Keyword Java Byte Keyword Java List Implementations Java Xml Parser Method Overriding in Java RMI program in Java Virtual Function in Java What is interpreter 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 What is anagram in Java? Accessors and Mutator in Java Bottom view of a binary tree in Java Convert List to String in Java Equidigital in Java How to check data type 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 How to Reduce Time Complexity 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 The final Keyword 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 Caesar Cipher Program 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 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 Tug of War in Java Types of Events in Java

Java Thread class

Thread class

The thread represents a part of the process. Every process can have multiple associated threads in which every thread may execute the same or different job. By default, each thread assigns a default priority by the JVM, which is used by thread scheduler to determine which thread must be run first. Thread class has various constructors and methods for creating and managing the behaviour of the threads.

 Thread class constructors:

  • Thread(): It creates a new Thread object.
  • Thread(Runnable target): It creates a new Thread object having a Runnable interface  as an argument.
  • Thread(Runnable target, String name): It creates a new Thread object having a Runnable target and String as an argument.
  • Thread(String name): It creates a new Thread object having String as an argument.
  • Thread(ThreadGroup group1, Runnable target1): It creates a new Thread object having Threadgroup and Runnable as an argument.
  • Thread(ThreadGroup group1, Runnable target1, String name1): It creates a new Thread object that has a specified name and targeted as its run object. The thread refers to the thread group referred to by the group1.
  • Thread(ThreadGroup grp, Runnable target2, String name1, long stackSize1): It creates a new Thread object having a target as its run object, has the specified name as its name1, the thread group(i.e., grp) have created thread and has the specified stack size1.
  • Thread(ThreadGroup group1, String name1): It creates a new thread object having Threadgroup and String as arguments.

Thread class Methods:

1. public String toString(): The toString() method of the Thread class is used to return the string representation of the thread, including the thread’s name, priority, and thread group.

Example:

public class Multithread implements Runnable   
 {   
 Thread t;  
 Multithread()   
 {  
 t = new Thread(this);  
  // this will call run() function   
  t.start();  
  }  
  public void run()   
  {  
  // returns a string representation of this thread    
  System.out.println(t.toString());  
  }   
  public static void main(String[] args)   
  {   
  new Multithread();  
  }   
 }   

Output:

Java Thread class

2. public void setContextClassLoader(ClassLoader classloader):

The context class loader will be the application’s class loader unless you explicitly change the thread’s context class loader. That means the context class loader can load the classes that application can load.

By using this method, we can set the context ClassLoader for the current thread. When a thread is created at that time, the context ClassLoader can be set.

Parameters:

Classloader: it is the context of ClassLoader for this Thread.

Exceptions:

SecurityException: This exception will occur if the current thread cannot set the context of ClassLoader.

3. public ClassLoader getContextClassLoader()

It returns the context ClassLoader of the current thread. If it returns null, it means it is indicating the system class loader or failing that the bootstrap class loader.

Example:

By using the setContextClassLoader() and  getContextClassLoader() we can set the  Context ClassLoader  and get the Context ClassLoader of the Thread.

public class Multithread implements Runnable {      
 Thread t;
 Multithread()
 {
 /*Passes the Runnable class object into the argument of the Thread class constructor.so that we can call start() method  of Thread class for running the run() method of the Runnable implemented class.*/ 
 t=new Thread(this);           
 t.start();
 }
 public void run()
 { 
 //It return the context ClassLoader of this Thread.
 ClassLoader c=t.getContextClassLoader();
 //It sets the context ClassLoader of this Thread.
 t.setContextClassLoader(c); 
 System.out.println("Class="+c.getClass());
 System.out.println("Parent="+c.getParent());
 }
 public static void main(String[] args) { 
 new Multithread();
 }
 } 

Output:

Java Thread class2

4. public final void setDaemon(boolean on)throws IllegalThreadStateException:

A thread can be set as daemon thread or a user thread. The Daemon thread is a low priority thread that runs in background to perform tasks such as garbage collection. The JVM terminates itself when all user threads finish their execution. The JVM does not have a concern that either a Daemon thread is running or not. Mostly background task is performed by the Daemon thread.

Parameters:

On:  It marks the thread as a daemon thread if it is true. It describes as user thread if it marks as false. 

If u have a thread t1, then t1.setDaemon(true) would make it Daemon thread.

t1.setDaemon(false) would make it user thread.

Exceptions:

IllegalThreadStateException- If this thread is alive.

5. public final boolean isDaemon():

It is used to test if the thread is a daemon thread or not. If the thread is a daemon, it returns true. Otherwise, it returns false.

Example:

Java program to demonstrate the way of working of the setDaemon() and isDaemon() method.

public class Multithread extends Thread {
 public Multithread(String name)
 {
 super(name);
 } 
 public void run()
 { 
 if(Thread.currentThread().isDaemon()) {
 System.out.println(getName()+"is Daemon thread");
 }
 else
 { 
 System.out.println(getName()+ "is User thread");
 }
 } 
 public static void main(String[] args) {
 Multithread t1=new Multithread("t1"); 
 Multithread t2=new Multithread("t2");
 Multithread t3=new Multithread("t3"); 
 t1.setDaemon(true);
 t1.start();
 t2.start(); 
 t3.setDaemon(true);
 t3.start();
 }
 } 

Output:

Java Thread class3

6. public final void setName(String name)

It changes the name of the thread with respect to the argument name.

Parameters:

name: It indicates the new name for the thread.

Exceptions:

SecurityException: If the current thread cannot change the thread name.

7. public final String getName()

It returns the current thread name.

Example:

import java.lang.*;
 public class Multithread implements Runnable {
  Thread t;
 public Multithread() {
  t = new Thread(this);
  // this will call run() function 
  t.start();
  } 
  public void run() {
 //sets the Thread name.
  t.setName("shifa");
  System.out.println("Thread name"+t);
  // prints thread name
  System.out.println("Thread = " + t.getName());
 } 
 public static void main(String[] args) {
 new Multithread();
 }
 } 

Output:

Java Thread class4

8. public final void setPriority(int prior)throws IllegalArgumentException:

 It changes the priority of the thread. A thread is assigned to the processor by the thread scheduler based on the priority of it. The thread always has some priority assigned to it by the JVM during its creation of the thread. The priority can either be given by the programmer explicitly or given by the JVM during the creation of the thread.

Parameters:

prior: It indicates the priority to be set for the thread.

Exceptions:

IllegalArgumentException: If the priority range is between MIN_PRIORITY to MAX_PRIORITY

9. public final int getPriority()

It returns the current thread priority.

Example: Using the setPriority() and getPriority() of the Thread.

import java.lang.*;
 public class Multithread extends Thread{
 public void run() {
 System.out.println("Inside run method");
  } 
 public static void main(String[] args) {
 Multithread t1= new Multithread();
 Multithread t2= new Multithread();
 System.out.println("t1 thread priority:"+t1.getPriority());
 System.out.println("t2 thread priority"+t2.getPriority());
 t1.setPriority(10); 
 t2.setPriority(5);
 System.out.println("After given the priority to each threads");
 System.out.println("t1 thread priority:"+t1.getPriority());
 System.out.println("t2 thread priority"+t2.getPriority());
 }
 } 

Output:

Java Thread class5

10. public static void sleep(long milliseconds1)throws InterruptedException:

It causes the currently executing thread to pause(sleep) for the specified number of milliseconds. Thread’s sleep() does not  cause to lose any monitors or locks, the current thread has acquired.

Parameters:

Milliseconds1: the length of time to sleep in milliseconds.

Exceptions:

InterruptedException:  It throws an exception when the thread is interrupted in the sleeping state by another thread.

11. public static void sleep(long  milliseconds1, int  nanoseconds1)throws InterruptedException:

It causes the currently executing thread to pause for the specified number of milliseconds1 and nanoseconds1. Thread’s sleep() does not cause to lose any monitors or locks, that the current thread has acquired.

Parameters:

Milliseconds1: the length of time to sleep in milliseconds.

Nanoseconds1: the time in a nanosecond to pause the thread.

Exceptions:

InterruptedException: It throws an exception when the thread is interrupted in the sleeping state by another thread.

Example:

public class Multithread {
 public static void main(String[] s1) throws InterruptedException {
 long start = System.currentTimeMillis();
 Thread.sleep(1000);
 Thread.sleep(1000,200);
 System.out.println("Sleep time in ms = "+(System.currentTimeMillis()-start)); 
 System.out.println("Sleep time in ms = "+(System.currentTimeMillis()-start));
 }
 } 

Output:

Java Thread class6

12. public void start()throws IllegalThreadStateException

Initially, It causes the thread to begin execution; then after the JVM calls the run() method of the thread for doing its task.

Exceptions:

IllegalThreadStateException: If the thread was already started.

13. public void run()

The complete working of the thread is written in the run() method. The run() method is called  usually using the start() method. The start() method call run() method for the execution of the thread.

Example:

public class Multithread extends Thread {
 public void run()
 {
 System.out.println("Current thread name:"+Thread.currentThread().getName()); 
 System.out.println("run() method called via start() method");
 }
 public static void main(String[] args) {
 Multithread t=new Multithread(); 
 t.start(); 
 } 
 } 

Output:

Java Thread class7

14. public static void yield()

This method causes the temporarily pause of the current thread and permit other threads to execute or complete its job. If the current executing thread is not doing anything important and if any other threads or processes need to be run at the same time, it is allowed to give permit that it should be run first than the current thread. Then the  current running thread is sent back to the Runnable state from the Running state.

Example:

class MyThread2 extends Thread
 { 
 public void run()
 {
 for(int i=0;i<5;i++) {
 System.out.println(Thread.currentThread().getName()+"in control");
 }
 }
 } 
 public class Multithread {
 public static void main(String[] args) {
  MyThread2 t=new MyThread2(); 
  t.start();
  for(int i=0;i<5;i++)
   {
  Thread.yield();
 System.out.println(Thread.currentThread().getName()+"in control");
   }
   }
 } 

Output:

Java Thread class8

15. public final void join()throws InterruptedException

The join() method is called ,when a  thread wants to wait until completing(die) the thread who called the join() method.

Exceptions:

InterruptedException: If any other thread has interrupted that thread who called the join()method.

16. public final synchronized void join(long millisecond)throws InterruptedException

The current thread waits until the thread on which it is called dead.

And also, the current thread waits in the specified time(milliseconds) for the thread dead, which calls the join method.

Parameters:

milliseconds: the time to wait in milliseconds.

Exceptions:

InterruptedException: If any thread is interrupted, thread who called the join() method.

17. public final synchronized void join(long milliseconds1, int nanoseconds1)throws InterruptedException

It causes the current thread on wait condition or sends the thread to the waiting state until the thread is dead on which join method is called, or the current thread waits for a specified time (milliseconds1+nanoseconds1) for the thread dead on which join method is called.

Parameters:

Milliseconds1+nanoseconds1:  The total time the thread has to wait for other threads.

Exceptions:

InterruptedException: If any thread is interrupted, the thread who called the join() method.

Example:

public class Multithread {
 public static void main(String[] args) {
  Thread thread1=new Thread(new Runnable1(),"thread1");
  Thread thread2=new Thread(new Runnable1(),"thread2");
  Thread thread3=new Thread(new Runnable1(),"thread3"); 
  thread1.start();
  //After 2 seconds wait or if the thread is dead second thread starts its execution.
   try
   {
  thread1.join(2000);
  } 
  catch(InterruptedException e)
  { 
 e.printStackTrace();
  }         
 thread2.start(); 
 //When first thread is dead then third thread starts.
 try
 {
 thread1.join(); 
 }catch(InterruptedException e)
 {
 e.printStackTrace();
 }
  thread3.start(); 
  //Before finishing main thread, all threads must be finished their execution.
 try
 { 
 thread1.join();
 thread2.join();
 thread3.join();
 }catch(InterruptedException e)
 { 
 e.printStackTrace();
 }
  System.out.println(“Before exiting main thread all threads are dead,");         
  }
 } 
 class Runnable1 implements Runnable{
 public void run()
 {
 System.out.println("Thread started"+Thread.currentThread().getName());
 try
 {
 Thread.sleep(4000);
 }
 catch(InterruptedException e)
 {
 e.printStackTrace();
 }
 System.out.println("Thread ended"+Thread.currentThread().getName());
 }
 } 

Output:

Java Thread class9

18. public boolean isInterrupted()

It is used to tests whether the thread has been interrupted or not. It returns true if this thread has been interrupted, otherwise return false.

19. public void interrupt()

This method is used to interrupt the thread. If any thread is in sleeping or waiting state, then using interrupt() method, we can interrupt the execution of that thread by showing InterruptedException.

Example:

class Thread1 extends Thread
 { 
 public void run()
 { 
 try 
 { 
 for(int i=0;i<5;i++) {
 Thread.sleep(1000);
 System.out.println("Shifa Thread1");
 }
 } 
 catch(InterruptedException e) {
 throw new RuntimeException("Thread Interrupted");
 }
 }
 }
 public class Multithread {
 public static void main(String[] args) {
 Thread1 t1=new Thread1(); 
 t1.setName("shifa Thread");
 t1.start();
 try
 {
 t1.interrupt();
 } 
 catch(Exception e)
 {
 System.out.println("Exception handled");
 }
 boolean a= t1.isInterrupted(); 
 System.out.println("Thread is interrupted or not "+a+"  "+"yes it is a interrupted thread ");
 }
 } 

Output:

Java Thread class10

20. public final boolean isAlive()

It tests whether the thread is alive or not. If thread is alive it returns true otherwise it returns false.

21. public Thread.State getState()

It returns the state of the thread, which called this method.

22. public long getId()

It returns the identifier of the current thread.

23. public static Thread currentThread()

The currently executing thread object is returned by the method.

Example:

class Thread1 extends Thread
 { 
 public void run()
 { 
 System.out.println("Shifa Thread1");
 }
 }
 public class Multithread {
 public static void main(String[] args) {
 Thread1 t1=new Thread1(); 
 Thread1 t2=new Thread1();
 t1.start();
 //It returns the state of the thread t1.
 System.out.println("t1 state ="+t1.getState()+" as start() method called before getState() method");
 //It returns the state of the thread t2.
 System.out.println("t2 state ="+t2.getState()+" as start() method called after getState() method");
 t2.start(); 
 System.out.println("current thread name ="+t1.currentThread());
 System.out.println("current thread name ="+t2.currentThread());
 System.out.println("t1 thread alive or not ="+t1.isAlive());
 System.out.println("t2 thread alive or not ="+t2.isAlive());
 System.out.println("t1 id is ="+t1.getId());
 System.out.println("t2 id is ="+t2.getId());
 }
 } 

Output:

Java Thread class11

24. public final ThreadGroup getThreadGroup()

It returns the thread group to which the thread belongs. ThreadGroup creates a group of threads. It offers a convenient way to manage groups of threads as a unit. This is particularly valuable in situation in which you want to suspend and resume a number of related threads.

25. public static int activeCount()

It returns an estimate of the number of active threads in the current thread’s thread group and in any other thread group that has the current thread’s thread group as an ancestor.

Example:

class Thread1 extends Thread
 { 
 Thread1(String threadname, ThreadGroup tgrp)
 {
 super(tgrp, threadname); 
 start();
 }
 public void run()
 { 
 for(int i=0;i<100;i++)
 {
 try
 { 
 Thread.sleep(10);
 }
 catch(InterruptedException ex)
 { 
 System.out.println("Exception encountered");
 }
 }
 }
 }
 public class Multithread {
  public static void main(String[] args) {
  //creating the ThreadGroup. 
 ThreadGroup threadgrp=new ThreadGroup("parent thread group");
  //Adding t1 thread into the ThreadGroup.
  Thread1 t1=new Thread1("one",threadgrp); 
  System.out.println("Starting first thread");
  //Adding t2 thread into the ThreadGroup.
  Thread1 t2=new Thread1("two",threadgrp);
  System.out.println("starting second thread");
  //checking the number of active thread.
  System.out.println("number of active thread in the ThreadGroup:"+threadgrp.activeCount()); 
  System.out.println("t1 thread belongs to the ThreadGroup  ="+t1.getThreadGroup());
  System.out.println("t2 thread belongs to the ThreadGroup  ="+t2.getThreadGroup());
     }       
 } 

Output:

Java Thread class12

26. public static int enumerate(Thread[] array1)

It is used to copy into the specified array every active thread in the current thread’s thread group and its subgroups.

Parameters:

array1: It returns the number of threads put into the array.

Example:

class Thread1 extends Thread
 { 
 Thread1(String thname, ThreadGroup tg)
 {
 super(tg,thname);
 start();
 } 
 public void run()
 {
 for(int i=0;i<5;i++)
 {
 try
 { 
 Thread.sleep(10);
 }
 catch(InterruptedException ex)
 {
 System.out.println("Exception encountered");
 } 
 System.out.println(Thread.currentThread().getName()+"completed exceuting");
 }
 }
 }
 public class Multithread { 
 public static void main(String[] args) {
 ThreadGroup thg1=new ThreadGroup("parent thread");
 ThreadGroup thg2=new ThreadGroup(thg1,"child thread");
 Thread1 t1=new Thread1("shifa Thread1",thg1);
 System.out.println("starting of Threda-1");
 Thread1 t2=new Thread1("shifa Thread2",thg2);
 System.out.println("starting of Threda-2");
 Thread[] group1=new Thread[thg1.activeCount()]; 
 int count=thg1.enumerate(group1);
 for(int i=0;i<count;i++)
 {
 System.out.println(group1[i].getName()+"found");
 }          
 }
 } 

Output:

Java Thread class13

27. public static Map<Thread, StackTracesElement[]> getAllStackTraces()

The stack traces map for all live threads is returned by the method. The threads are represented as threads and each map value represents an array of StackTraceElement that specifies the stack dump of the corresponding Thread.

Example:

import java.util.Map;
 public class Multithread implements Runnable{
 public void run()
 {
 System.out.println("This is run() method");
 } 
 public static void main(String[] args) {
 Multithread t1=new Multithread();
 Thread t=new Thread(t1);
 t.start();
 Map m1=Thread.getAllStackTraces();
 System.out.println(m1.toString());
 }
 } 

Output:

Java Thread class14

28. public final void suspend()

This method puts the thread from running to waiting state. This method is used if you want to stop the thread execution. This method allows a thread to temporarily cease execution. The suspended thread can be resumed using the resume() method.

29. public final void resume()

It is used to resume a thread which was suspended using suspend() method. This method allows the suspended thread to start again.

Example:

class Multithread1 implements Runnable{
 String name; // name of thread
 Thread t;
 Multithread1(String threadname) {
 name = threadname;
 t = new Thread(this, name); 
 System.out.println("New thread: " + t);
 t.start(); // Start the thread
 }
 // This is the entry point for thread.
 public void run() {
 try {
 for(int i = 7; i > 0; i--) { 
 System.out.println(name + ": " + i);
 Thread.sleep(200);
 }
 } catch (InterruptedException e) {
 System.out.println(name + " interrupted.");
 }
 System.out.println(name + " exiting.");
 }
 }
 public class Multithread {
 public static void main(String args[]) { 
 Multithread1 ob1 = new Multithread1("One");
 Multithread1 ob2 = new Multithread1("Two");
 try {
 Thread.sleep(1000);
 ob1.t.suspend(); 
 System.out.println("Suspending thread One");
 Thread.sleep(1000);
 ob1.t.resume();
 System.out.println("Resuming thread One");
 ob2.t.suspend(); 
 System.out.println("Suspending thread Two");
 Thread.sleep(1000); 
 ob2.t.resume();
 System.out.println("Resuming thread Two");
 } catch (InterruptedException e) {
 System.out.println("Main thread Interrupted");
 }
 // wait for threads to finish
 try { 
 System.out.println("Waiting for threads to finish.");
 ob1.t.join();
 ob2.t.join();
 } catch (InterruptedException e) {
 System.out.println("Main thread Interrupted");
 } 
 System.out.println("Main thread exiting.");
 }
 } 

Output:

Java Thread class15

UncaughtExceptionHandler:

Java handle Runtime(uncaught) Exceptions that we might not have handled in our program.

UncaughtException can be set (handle) at three levels.

  1. Thread.setDefaultUncaughtExceptionHandler
  2. Thread.setUncaughtExceptionHandler
  3. ThreadGroup.uncaughtException

Examples of Uncaught Exception:

30.  public static void setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler uncatch_exec)

This method sets the default handler invoked, which arises when the thread terminates abruptly due to an uncaught exception, and no other handler has been defined for that thread.

Parameters:

uncatch_exec: The instance is used as the default uncaught exception handler. There is no default handler if it is null.

Example: Using Thread.setDefaultUncaughtExceptionHandler.

public class Multithread extends Thread {
 public static void main(String s1[])
 {
 Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler(){
 public void uncaughtException(Thread t,Throwable e)
 { 
 System.out.println(t.getName()+"thread end with following exception");
 System.out.println(e.getMessage());
 }
 });
 Thread t1=new Thread(new MyThread1(),"T1");
 t1.start();
 }
 } 
 class MyThread1 implements Runnable
 {
 public void run()
 {
 for(int i=1;i<=10;i++)
 { 
 System.out.println(Thread.currentThread().getName()+"i="+i);
 if(i==5)
 {
 throw new RuntimeException("My Runtime Exception....");
 }
 }
 } 
 } 

Output:

Java Thread class16

31. public void setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler excep_handler)

This method is used to set the handler called if any of the thread terminates abnormally due to uncaught exception if an exception arises.

Parameters:

excep_handler: It is the handler object to use when this thread terminates abnormally due to an uncaught exception.

Example: using Thread.setUncaughtExceptionHandler

public class Multithread extends Thread {
 public static void main(String s2[])throws Exception
 {
 Thread.currentThread().setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler(){ 
 public void uncaughtException(Thread t,Throwable e)
 {
 System.out.println(t.getName()+"thread end with following exception");
 System.out.println(e.getMessage());
 }
 }); 
 throw new Exception("exception thrown from somewhere in your program"); 
 }} 

Output:

Java Thread class17

32. public void uncaughtException(Thread t, Throwable e) 

This method is called by the Java Virtual Machine when a thread in this thread group stops because of an uncaught exception, and the thread does not have a specific Thread.UncaughtExceptionHandler installed.

Parameters:

The t: indicates that this is the thread that is about to exit.

The e: indicates this is the uncaught exception.

Example: Using the ThreadGroup.uncaughtException

public class Multithread extends Thread {
 public static void main(String s4[])throws Exception
 {
 MyThreadGroup myThreadGroup=new MyThreadGroup("myThreadGroup");
 Thread t1=new Thread(myThreadGroup, new MyThread1(),"T1"); 
 t1.start();
 }
 }
 class MyThreadGroup extends ThreadGroup
 { 
 public MyThreadGroup(String name)
 {
 super(name);
 }
 public void uncaughtException(Thread thread, Throwable t)
 { 
 ThreadGroup threadGroup=thread.getThreadGroup();
 System.out.println(threadGroup);
 System.out.println(thread.getName()+"thread end with following exception...."); 
 System.out.println(t.getMessage());
 }
 } 
 class MyThread1 implements Runnable
 {
  public void run()
  { 
  for(int i=1;i<=10;i++)
  {
  System.out.println(Thread.currentThread().getName()+" ,i="+i);
  if(i==5)
  { 
  throw new RuntimeException("My Runtime exception");
  }
 }
 }
 } 

Output:

Java Thread class18

33. public static Thread.UncaughtExceptionHandler getDefaultUncaughtExceptionHandler()

It returns the default handler invoked which arise if a thread abruptly terminates when there is an occurring an uncaught exception.

Example:

import java.lang.*;
 public class Multithread implements Runnable {
 Thread t;
 public Multithread() {
  t = new Thread(this); 
  // this will call run() function
  t.start();
    }
  public void run() {
  // prints thread name 
  System.out.println("Thread = " + t.getName());
   /*It returns the default handler invoked which arise if a thread abruptly         terminates when there is an occurring an uncaught exception. */
 Thread.UncaughtExceptionHandler handler = Thread .getDefaultUncaughtExceptionHandler(); 
  System.out.println(handler);
  } 
  public static void main(String[] args) {
  new Multithread(); 
 } 
 } 

Output:

Java Thread class19

34. public Thread.getUncaughtExceptionHandler getUncaughtExceptionHandler()

 It returns the handler invoked when this thread abruptly terminates due to an uncaught exception.

Example:

import java.lang.*;
 public class Multithread implements Runnable {
  Thread t;
 public Multithread() {
  t = new Thread(this);
  // this will call run() function
  t.start();
  } 
  public void run() {
  // prints thread name
  System.out.println("Thread = " + t.getName());
 /* It returns thehandler invoked which arise if a thread abruptly
          terminates when there is an occurring an uncaught exception.  */
  Thread.UncaughtExceptionHandler handler =  
  public static void main(String[] args) {
  new Multithread(); 
 new Multithread();
  } 
 } 

Output:

Java Thread class20



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