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What is the use of Join method in Java?

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What is the use of Join method in Java?
posted Dec 15, 2014 by Dominic

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1 Answer

+2 votes

The join method allows one thread to wait for the completion of another.

If " t " is a Thread object whose thread is currently executing,
t.join();
Causes the current thread to pause execution until t’s thread terminates.

Overloads of join allow the programmer to specify a waiting period. However, as with sleep, join is dependent on the OS for timing, so you should not assume that join will wait exactly as long as you specify.

Like sleep, join responds to an interrupt by exiting with an InterruptedException.

answer Dec 16, 2014 by Karthick.c
Similar Questions
+2 votes
import java.util.ArrayList;
import java.util.List;

public class ThreadB extends Thread {
    private static List<String> list1   = new ArrayList<String>();
    private static List<String> list2   = new ArrayList<String>();
    private static final Object mutex   = new Object();

    public void run() {
        try {
            sleep(2000l);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        synchronized (mutex) {
            list1.add("Hello");
            System.out.println("Added for 1   " + list1.size());
            list2.add("Added for 2");
            System.out.println("Added for 2   " + list2.size());
            mutex.notify();
        }
    }

    public static void main(String[] args) {
        ThreadB a1 = new ThreadB();
        ThreadB a2 = new ThreadB();
        a1.start();
        a2.start();
        new ThreadB().m1();    
    }

    private void m1() {         
        synchronized (list1) {
            System.out.println(list1.size());
            System.out.println(list2.size());
            try {
                list1.add("hello");
                System.out.println("m1  :::   " + list1.size());
                sleep(5000l);
                System.out.println("Oh mY God");
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    }
}

Output is

0
0
m1  :::   1
Added for 1   2
Added for 2   1
Added for 1   3
Added for 2   2
Oh mY God

After locking list1, how other threads are going to access that list?

...