Question

giving the following

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MB5Returner extends Thread {

    private int startPoint;
    private int endPoint;

    public void run() {
        for (int i = startPoint; i < endPoint; i++) {
            try {
                String val = Words.allPossible.get(i);
                MessageDigest m;

                m = MessageDigest.getInstance("MD5");

                m.update(val.getBytes(), 0, val.length());
                String hashed = new BigInteger(1, m.digest()).toString(16);

            //  System.out.println("MD5 = " + hashed);
                checkMD5(hashed, val);

            } catch (NoSuchAlgorithmException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (FoundMD5Exception e) {

            }
        }
    }

    private void checkMD5(String hashed, String val) throws FoundMD5Exception {
        if (hashed.equals(Main.hashedPassword)) {
            throw new FoundMD5Exception(hashed, val);
        }
    }

    public MB5Returner(int startPoint, int endPoint) {
        super();
        this.startPoint = startPoint;
        this.endPoint = endPoint;
    }

}

I’m making few of threads like this one. How can I stop all of them if my exception FoundMD5Exception was catched in one of them?

Answer 1

The simplest solution is probably to create an AtomicBoolean (call it keepRunning or something similar). Pass it as a reference to the constructor of MB5Returner:

public class MB5Returner extends Thread {

    // ...
    private AtomicBoolean keepRunning;

    MB5Returner(AtomicBoolean keepRunning) {
        this.keepRunning = keepRunning;
    }

Change the for-loop into

for (int i = startPoint; keepRunning.get() && i < endPoint; i++) {
                         ^^^^^^^^^^^^^^^^^

Then simply do

    // ...
} catch (FoundMD5Exception e) {
    keepRunning.set(false);
}