Question on sleep() method from dan's

[aishwarya mathur]

Please have a look at the below code:

class Example extends Thread {
private int i;
public void run() {
try {
sleep(1000);
}
catch(InterruptedException e) {
System.out.println("xyz");
}
}
public static void main(String args[]) {
Example e = new Example();
e.start();
System.out.println(e.i);
}
  

I thought as sleep() is a static method,it should always be invoked as Thread.sleep(),also I considered the syntax for sleep() above code results in compiler error... But it isn't it...why? Please put some light into it.

[Sandeep Jindal]

Hi Aishwarya,

The sleep method is static method of Thread class. Thats very true.
But who says that static method can only be called using ClassName.staticMethod()

You can always call static method from the instance. So you code:
sleep(500) is something like this.sleep(500);

which is very well justified.

Hope this clears.

Regards,
Sandeep Jindal

[marc weber]

As a static method, it's good coding practice to call sleep() from the parent class Thread, but this is not required.

EXAM TIP: Note that sleep always executes on the currently running Thread. So when sleep() is called using a specific instance of Thread, it can be misleading. For example, if you have two Threads, t1 and t2, and within t1 is the statement, t2.sleep(), then it might appear that t2 is being put to sleep. But actually, the current Thread (t1) is put to sleep -- it just happened to call the static sleep() method from another instance.
[ September 16, 2004: Message edited by: marc weber ]

[Sandeep Jindal]

Hi Marc,

Thats nice explaination. Thats clears my boubt that why my IDEs give warnings when i used call a static method from an instance variable, here is the catch.

Regrads
Sandeep Jindal