this.yield ??

[Gary Marshall]

Please confirm my answer to the following question:
What is the result of compiling and runing the following code?

class MyThread implements Runnable{
public void run() {
System.out.print("go ");
this.yield();   //LINE 1
System.out.print("gogo");
 }
 
public static void main(String [] args) {
    (new MyThread()).run();
 }
}

I say that you cannot use "this" with yield, since yield is a static method and therefore this code will not compile at LINE 1.

Can anybody concurr?
thank you
g
[ September 24, 2007: Message edited by: Gary Marshall ]

[fred rosenberger]

Well, we can't confirm you answer unless you tell us what your answer is. Have you tried compiling and running this to see what happens? that's probably going to be faster than asking someone here.

[dolly shah]

Fred is right, try it by yourself. Anyways I ran it & I got compiler error at line 1 "cannot fine symbol method yield()".

[ahmed yehia]

I say that you cannot use "this" with yield, since yield is a static method and therefore this code will not compile at LINE 1.

Its ok to use this on static members.
Remember where yield() is defined so you can fix your program.

[sridhar row]

Its ok to use this on static members.

Can somebody show me with an example how this can be used on static members. Thanks

[Eduardo Mendes]

If your class extends Thread, rather than implementing Runnable, then the code will be running fine (if you call a static method on an instance of the class, the compiler will replace that line of code with an actual call to the class instead, i.e. this.yield() becomes Thread.yield())

class MyThread extends Thread {
public void run() {
System.out.print("go ");
this.yield(); //LINE 1
System.out.print("gogo");
}

public static void main(String [] args) {
(new MyThread()).run();
}
}

[sridhar row]

Hi Edwardo,
whats the difference between the two? why it does not work if class is implementing. Both means the same in both cases we are overriding run method and reference is class instance. Thanks.

[Henry Wong]

Originally posted by sridhar row:
Hi Edwardo,
whats the difference between the two? why it does not work if class is implementing. Both means the same in both cases we are overriding run method and reference is class instance. Thanks.

In the first case, the class is a Runnable. In the second case, the class is both a Thread object and a Runnable. Since the yield() method is a method of the Thread class, being a Runnable object is not good enough -- you have to be a Thread object to have the yield() method.

Henry

[sridhar row]

Thanks Henry. Makes perfect sense!!

[Eduardo Mendes]

Sridhar, I am just not sure you have the answer to your original question. If the question was put to you as you have transcribed it here (with implements Runnable rather then extends Thread) than it is wrong, and this.yield() would never even compile, for the reasons mentioned in the previous two posts.