Execute pairwise threads concurrently

Question

class A
{
    public void func()
    {
        new Thread()
        {
            public void run()
            {
                // statements
            }
        } .start();
        new Thread()
        {
            public void run()
            {
                // statements
            }
        } .start();
        new Thread()
        {
            public void run()
            {
                // statements
            }
        } .start();
        new Thread()
        {
            public void run()
            {
                // statements
            }
        } .start();
    }
}

Here, I'm trying the first two threads (say pair A) to run concurrently and the next two threads (say pair B) to run concurrently only after pair A has finished executing.

Also if anybody can explain if it can be achieved via java.util.concurrent or threadgroup. I'll really appreciate any help done.

Answer 1

public void func()
{
    Thread a = new Thread()
    {
        public void run()
        {
            // statements
        }
    }
    Thread b = new Thread()
    {
        public void run()
        {
            // statements
        }
    }
    a.start();
    b.start();
    a.join();  //Wait for the threads to end();
    b.join();
    new Thread()
    {
        public void run()
        {
            // statements
        }
    } .start();
    new Thread()
    {
        public void run()
        {
            // statements
        }
    } .start();
}