Java join thread control usage

The JDK description:

The join
Public final void the join ()
                              Throws InterruptedException waits for the thread to terminate.

Throws:
InterruptedException - if any thread interrupts the current thread. When the exception is thrown, the interrupted state of the current thread is cleared
Test code:

public class MyThread extends Thread { 

    public static void main(String[] args) throws InterruptedException { 
        A a=new A(); 
        B b=new B(); 
        a.start(); 
        a.join(); 
        b.start(); 

    } 
} 
class A extends Thread{ 

    public void run(){ 
        for(int i=0;i<10000;i++){ 
            System.out.print("A   "+i); 
        } 
    } 
} 

class B extends Thread{ 

    public void run(){ 
        for(int i=0;i<10000;i++){ 
            System.out.print("B   "+i); 
        } 
    } 
} 

You can see that thread B doesn't start executing until thread A has finished executing

Very clear is not ha ha