The join() method

The join() method waits for a thread to die. In other words, it causes the currently running threads to stop executing until the thread it joins with completes its task.

Syntax

public void join()throws InterruptedException

public void join(long milliseconds)throws InterruptedException

Example #1

Example of join() method

snippet

class TestJoinMethod1 extends Thread{
 public void run(){
  for(int i=1;i<=5;i++){
   try{
    Thread.sleep(500);
   }catch(Exception e){System.out.println(e);}
  System.out.println(i);
  }
 }
public static void main(String args[]){
 TestJoinMethod1 t1=new TestJoinMethod1();
 TestJoinMethod1 t2=new TestJoinMethod1();
 TestJoinMethod1 t3=new TestJoinMethod1();
 t1.start();
 try{
  t1.join();
 }catch(Exception e){System.out.println(e);}

 t2.start();
 t3.start();
 }
}

Output

Output:1 2 3 4 5 1 1 2 2 3 3 4 4 5 5

As you can see in the above example,when t1 completes its task then t2 and t3 starts executing.

Example #2

Example of join(long miliseconds) method

snippet

class TestJoinMethod2 extends Thread{
 public void run(){
  for(int i=1;i<=5;i++){
   try{
    Thread.sleep(500);
   }catch(Exception e){System.out.println(e);}
  System.out.println(i);
  }
 }
public static void main(String args[]){
 TestJoinMethod2 t1=new TestJoinMethod2();
 TestJoinMethod2 t2=new TestJoinMethod2();
 TestJoinMethod2 t3=new TestJoinMethod2();
 t1.start();
 try{
  t1.join(1500);
 }catch(Exception e){System.out.println(e);}

 t2.start();
 t3.start();
 }
}

Output

Output:1 2 3 1 4 1 2 5 2 3 3 4 4 5 5

In the above example,when t1 is completes its task for 1500 miliseconds(3 times) then t2 and t3 starts executing.

getName(),setName(String) and getId() method

public String getName()
public void  setName(String name)
public long getId()

Example

snippet

class TestJoinMethod3 extends Thread{
  public void run(){
   System.out.println("running...");
  }
 public static void main(String args[]){
  TestJoinMethod3 t1=new TestJoinMethod3();
  TestJoinMethod3 t2=new TestJoinMethod3();
  System.out.println("Name of t1:"+t1.getName());
  System.out.println("Name of t2:"+t2.getName());
  System.out.println("id of t1:"+t1.getId());

  t1.start();
  t2.start();

  t1.setName("Sonoo Jaiswal");
  System.out.println("After changing name of t1:"+t1.getName());
 }
}

Output

Output:Name of t1:Thread-0 Name of t2:Thread-1 id of t1:8 running... After changling name of t1:Sonoo Jaiswal running...

The currentThread() method

The currentThread() method returns a reference to the currently executing thread object.

Syntax

public static Thread currentThread()

Example

Example of currentThread() method

snippet

class TestJoinMethod4 extends Thread{
 public void run(){
  System.out.println(Thread.currentThread().getName());
 }
 }
 public static void main(String args[]){
  TestJoinMethod4 t1=new TestJoinMethod4();
  TestJoinMethod4 t2=new TestJoinMethod4();

  t1.start();
  t2.start();
 }
}

Output

Output:Thread-0 Thread-1