how to override thread.start() method in java?

Question

I need to implement thread.start() method in my java code. Please let me know through an example of overriding of thread.start() method and how it works?

Answer 1

Agree with Schildmeijer, don't override start, override run() instead.

In fact, although start can be overridden (it's not final), it calls the native start0 method which in turn will cause the VM to call the run method (actually from the context of a native thread/process). The native start0 method has private access, so even if you overrode the start, I can't see how you could reproduce the affect.

The client calling start() is within a thread (lets say, the main thread), it's not until the run method has done its thing that another thread will be spawned.

Take a look at the Sun (ahem, Oracle) tutorial on threads at http://download.oracle.com/javase/tutorial/essential/concurrency/index.html, in particular the section on starting threads.

Answer 2

We can override start/run method of Thread class because it is not final. But it is not recommended to override start() method

class Bishal extends Thread { 
public void start() 
    { 
        System.out.println("Start Method"); 
    } 
public void run() 
    { 
        System.out.println("Run Method"); 
    } 
} class Main{ 
public static void main(String[] args) 
    { 
        Bishal thread = new Bishal(); 
        thread.start(); 
        System.out.println("Main Method"); 
    } 
} 

when we are calling start() method by an object of Bishal class, then any thread won’t be created and all the functions are done by main thread only.

Answer 3

class Worker implements Runnable{

public void run(){ if("foo"){ runFoo(); } else { runBar(); } }

private void runFoo(){ // something }

private void runBar(){ // else }

}

I'm pretty sure, you needn't to overwrite the start-Method.

By the way: Take al look at java.util.concurrent.Callable

http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/Callable.html

Answer 4

You don't override the start, you override the "run". You can simply implement a thread by:

new Thread() {
  public void run() {
    //your code here
  }
}.start();
//start will call the logic in your run method