6 replies to this topic

[dusch]

I need implementation of methods suspend() and resume(), using wait() and notify(), but without using active waiting.

[lethalwire]

What do you have so far?

[dusch]

I don't have anything, that is a homework task..
It supposed to be as simple as possible..
And, it's for tomorrow, so please, help! :)

[lethalwire]

Try googling around for information on wait and notify in java. There are tons of resources on this subject.

[dusch]

I tried, but I didn't find what I am looking for..
I wrote this peace of code, but I know it's not good, it should be process for
that is the suspend() called get to sleep, not process that is calling suspend(), and I do not know how to do it right.

import java.util.concurrent.*;

public class Domaci1 {
private boolean bad=false;

public synchronized void methodSuspend() {
while(bad=true) {
try {
wait();
} catch(InterruptedException e) {

}
}
}
public synchronized void methodResume() {
if(bad=false) {
notify();
}
}

}

[wim DC]

I didn't actually run the code, but this would seem better. As you didn't really use your "bad" boolean a lot, or at least wrong.
You need 2x"=" to check for equality, otherwise you just change the boolean's value.

So something like this would already be a step closer.

import java.util.concurrent.*;

public class Domaci1 {
  private boolean suspend = false;


  public synchronized void methodSuspend() {
    while(suspend) {
      try {
        wait();
      } catch(InterruptedException e) { }
    }
  }


  public synchronized void methodResume() {
    if(suspend) {
      suspend = false;
      notify();
    }
  }
}

But, to actually call wait and notifiy on an Object you need the Object's lock. This is done using the "synchronize" keyword. I am however unsure if you can actually synchronize yourself...

[dusch]

Thank you very much for the solution, and thanks for reminding, I know it's a "==" but I've accidentally made a mistake..