How to create thread

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.

Constructors of Thread class

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

Methods of Thread class

1. public void run(): is used to perform action for a thread.
2. public void start(): starts the execution of the thread.JVM calls the run() method on the thread.
3. public void sleep(long miliseconds): Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds.
4. public void join(): waits for a thread to die.
5. public void join(long miliseconds): waits for a thread to die for the specified miliseconds.
6. public int getPriority(): returns the priority of the thread.
7. public int setPriority(int priority): changes the priority of the thread.
8. public String getName(): returns the name of the thread.
9. public void setName(String name): changes the name of the thread.
10. public Thread currentThread(): returns the reference of currently executing thread.
11. public int getId(): returns the id of the thread.
12. public Thread.State getState(): returns the state of the thread.
13. public boolean isAlive(): tests if the thread is alive.
14. public void yield(): causes the currently executing thread object to temporarily pause and allow other threads to execute.
15. public void suspend(): is used to suspend the thread(depricated).
16. public void resume(): is used to resume the suspended thread(depricated).
17. public void stop(): is used to stop the thread(depricated).
18. public boolean isDaemon(): tests if the thread is a daemon thread.
19. public void setDaemon(boolean b): marks the thread as daemon or user thread.
20. public void interrupt(): interrupts the thread.
21. public boolean isInterrupted(): tests if the thread has been interrupted.
22. 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().

1. 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

class Multi extends Thread{
public void run(){
System.out.println("thread is running...");
}
public static void main(String args[]){
Multi t1=new Multi();
t1.start();
 }
}

2) Java Thread Example by implementing Runnable interface

class Multi3 implements Runnable{
public void run(){
System.out.println("thread is running...");
}

public static void main(String args[]){
Multi3 m1=new Multi3();
Thread t1 =new Thread(m1);
t1.start();
 }
}

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.