Threads

[ssiva raman]

hi

i've seen no argument thread constructor ie., Thread();

but what's use of that? doesn't the thread useless without a job(Runnable)?

is there anyother reason behind that no argument Thread.?

help me get over this ?

thanks

[Henry Wong]

ssiva raman wrote:
i've seen no argument thread constructor ie., Thread();

but what's use of that? doesn't the thread useless without a job(Runnable)?

is there anyother reason behind that no argument Thread.?

Although not recommended, you can also subclass from the Thread class.

Henry

[ssiva raman]

but Mr.henry what is the point of subclassing the Thread?
instead we can create new Thread and pass it with different runnable object?

[R. Jain]

ssiva raman wrote:is there anyother reason behind that no argument Thread.?

It simplifies your task of creating an anonymous subclass of Thread on the run like this:

new Thread() {
    public void run() {
        System.out.println("Thread Executing");
    }
}

If there wasn't any 0-arg constructor in Thread, then the anonymous subclass would have to invoke the parameterized constructor explicitly, which you can't do.

[ssiva raman]

public class MyRunnable implements Runnable
{
public void run()
{
qo();
}
public void go ()
{
doMore() ;
}
public void doMore() 
{
System .out.println("top 0' the stack");
}
}
class ThreadTestDrive {
public static void main (String[] args) 
{
Runnable threadJob = new MyRunnable () ;
Thread myThread = new Thread (threadJob) ;
myThread .start();
}
}

i've studied threads using above sort of code i.e, implementing runnable in different class and passing its reference to Thread constructor.and there is no use of Thread otherwise.
your code is bit of strange to me.perhaps i'm not having a deep knowledge in threads.so can you please elaborate your code,if you dont bother, in the sense how do implement run() method in Thread unless you implement runnable in that class.

[R. Jain]

ssiva raman wrote:in the sense how do implement run() method in Thread unless you implement runnable in that class.

Thread class itself implements Runnable and has overridden the run() method which looks like this:

    @Override
    public void run() {
        if (target != null) {
            target.run();
        }
    }

Source Here. So, when you create a class implementing Runnable, and pass it's instance to the Thread constructor, the run() method of Thread will in turn call the run() method in your class. But if you just want to create a single thread, then it might not make much sense to create a separate class for this. This is where comes the use of anonymous inner class. The syntax like below:

new Thread() {
    @Override
    public void run() {

    }
}

... creates an anonymous subclass of Thread class, and overrides the run() method. Now, invoking the start() on that instance will call the run() method you have overridden there. So, it is giving you the similar outcome as you get by creating a different class implementing Runnable.

[ssiva raman]

does Thread class implicitly implements Runnable?

[R. Jain]

ssiva raman wrote:does Thread class implicitly implements Runnable?

Yes. It does. You always have the javadoc to see these stuffs.