Java - Stuck after instantiating an object

Question

I have a class, that needs to generate from time to time, a key and share it with a client and a server.

Kdc Class:

    protected Kdc() {
    (do stuff)
    runKdc();
} 


private void runKdc(){
    for(;;){
        generateKey();
        informClients();
        informServers();
        try {
            Thread.sleep(generationTime);
        } catch (InterruptedException e) {
            System.out.println("Sleep Interrupted");
        }
    }
}

Main class:

    public static void main(String[] args) {
    Kdc kdc = new Kdc();
    System.out.println("done"); //Doesn't reach the line
}

Now my problem is that i need to do something after starting the Kdc class and i can't! Because of the infinite loop, it just gets stuck in the Main class, after starting the Kdc class. Any ideas?

Thank you.

Answer 1

As other have said you should create the Kdc in it's own thread, for example

package com.testingarea;

class Kdc {

  public Kdc() {
    runKdc();
  }

  private void runKdc() {
    while(true) {
      System.out.println("Running kdc");
      try {
        Thread.sleep(5000);
      } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
    }
  }

}

class RunKdc implements Runnable {

  @Override
  public void run() {
    Kdc k = new Kdc();      
  }

}

public class TestThread {

  public static void main(String[] args) {
    new Thread(new RunKdc()).start();
    System.out.println("Kdc thread started");
  } 


}

Answer 2

You should run your KDC in a sperate thread. This thread will run in the background, and your main method will proceed.

And for this loop:

while(true){
    //do something
}

is much better than your for(;;){} loop. Replace the "true" by a boolean variable like "running" or "active"

Answer 3

Start the Kdc class in a new Thread, or creat a timer for executing kdc.runKdc(). You can creat the instance in the new thread like in the example below, or only run the code of runKdc() in a new thread.

public static void main(String[] args) 
{
    Thread keyGenerationThread= new Thread() 
    {
        @Override
        public void run() 
        {
            Kdc kdc = new Kdc();
        }
    };
    keyGenerationThread.start(); 
    System.out.println("done"); 
}