class A implements Runnable { public void run() { for(int i=0; i<20; i++) { System.out.println("Hi"); try { Thread.sleep(10); } catch(InterruptedException e) { System.out.println(e); } } } } class B implements Runnable { public void run() { for(int i=0; i<20; i++) { System.out.println("Hello"); try { Thread.sleep(10); } catch(InterruptedException e) { System.out.println(e); } } } } public class Runnable_Demo { public static void main(String[] args) { Runnable obj1=new A(); Runnable obj2=new B(); Thread t1=new Thread(obj1); Thread t2=new Thread(obj2); t1.start(); t2.start(); } }