How to create thread in Java?

There are two ways to create a thread:

1. By extending Thread class
2. By implementing Runnable interface.

---

Thread class:

Thread class provide constructors and methods to create and perform operations on a thread.Thread class extends Object class and implements Runnable interface.

Commonly used Constructors of Thread class:

Thread() Thread(String name) Thread(Runnable r) Thread(Runnable r,String name)

Commonly used methods of Thread class:

public void run(): is used to perform action for a thread. public void start(): starts the execution of the thread.JVM calls the run() method on the thread. public void sleep(long miliseconds): Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds. public void join(): waits for a thread to die. public void join(long miliseconds): waits for a thread to die for the specified miliseconds. public int getPriority(): returns the priority of the thread. public int setPriority(int priority): changes the priority of the thread. public String getName(): returns the name of the thread. public void setName(String name): changes the name of the thread. public Thread currentThread(): returns the reference of currently executing thread. public int getId(): returns the id of the thread. public Thread.State getState(): returns the state of the thread. public boolean isAlive(): tests if the thread is alive. public void yield(): causes the currently executing thread object to temporarily pause and allow other threads to execute. public void suspend(): is used to suspend the thread(depricated). public void resume(): is used to resume the suspended thread(depricated). public void stop(): is used to stop the thread(depricated). public boolean isDaemon(): tests if the thread is a daemon thread. public void setDaemon(boolean b): marks the thread as daemon or user thread. public void interrupt(): interrupts the thread. public boolean isInterrupted(): tests if the thread has been interrupted. public static boolean interrupted(): tests if the current thread has been interrupted.

Runnable interface:

The Runnable interface should be implemented by any class whose instances are intended to be executed by a thread. Runnable interface have only one method named run().

public void run(): is used to perform action for a thread.

---

Starting a thread:

start() method of Thread class is used to start a newly created thread. It performs following tasks: A new thread starts(with new callstack). The thread moves from New state to the Runnable state. When the thread gets a chance to execute, its target run() method will run.

---

1) Java Thread Example by extending Thread class

1. class Multi extends Thread{  
2. public void run(){  
3. System.out.println("thread is running...");  
4. }  
5. public static void main(String args[]){  
6. Multi t1=new Multi();  
7. t1.start();  
8.  }  
9. }  

Output:thread is running...

---

2) Java Thread Example by implementing Runnable interface

1. class Multi3 implements Runnable{  
2. public void run(){  
3. System.out.println("thread is running...");  
4. }  
5.   
6. public static void main(String args[]){  
7. Multi3 m1=new Multi3();  
8. Thread t1 =new Thread(m1);  
9. t1.start();  
10.  }  
11. }  

Output:thread is running...

If you are not extending the Thread class,your class object would not be treated as a thread object.So you need to explicitely create Thread class object.We are passing the object of your class that implements Runnable so that your class run() method may execute.