Isalive & Join Method

public class Main{
    public static void main(String args[]){
        NewThread ob1 = new NewThread("one");
        NewThread ob2 = new NewThread("two");
        NewThread ob3 = new NewThread("three");
        System.out.println("Thread one is alive " + ob1.t.isAlive());
        System.out.println("Thread two is alive " + ob2.t.isAlive());
        System.out.println("Thread three is alive " + ob3.t.isAlive());
        try{
            System.out.println("Waiting for threads to finish");
            ob1.t.join();
            ob2.t.join();
            ob3.t.join();
        }catch(InterruptedException e){
            System.out.println("Main thread Interrupted");
        }
        System.out.println("Thread one is alive " + ob1.t.isAlive());
        System.out.println("Thread two is alive " + ob2.t.isAlive());
        System.out.println("Thread three is alive " + ob3.t.isAlive());
    }
}
public class NewThread implements Runnable{
    String name;
    Thread t;
    NewThread(String threadname){
        name = threadname;
        t = new Thread(this,name);
        System.out.println("New Thread: " + t);
        t.start();
    }
    public void run(){
        try{
            for(int i=5;i>0;i--){
                System.out.println(name + " " + i );
                Thread.sleep(500);
            }
        }catch(InterruptedException e){
            System.out.println(name + "Interrupted");
        }
        System.out.println(name + "Exiting");
    }
}