Introduction to Programming

Extending Thread vs implementing Runnable

Implementing Runnable has the advantage (and in some cases, the only possible option) of allowing the implementation to extend another class. It is particularly helpful when you would like to add thread-like behavior to an existing class:

public class BRunnable extends SomeClass implements Runnable {  int i;   BRunnable(int i, String s) {    super(s);    this.i = i;  }  public int calculateSomething(double x) {    //calculate result    return result;  }  public void run() {    //any code you need goes here  }}

You can even invoke the method run() directly, without passing the object into the Thread constructor: 

BRunnable obj = new BRunnable(2, "whatever");int i = obj.calculateSomething(42d);obj.run(); Thread thr = new ...