Using threads for animation in a non-main class.

I am trying to create an abstract class that will control any JComponent with the arrow keys when extended, but I don't know how. Right now, I havent added a KeyAdapter for the arrow keys, but I have added a run method that calls another method called "move" which is supposed to print the word "hello" in the output every 33 milliseconds. Once I quit the application, all of the "hello"s hit me at once, but they are not timed. Here is my code so far.

Main Class:

Code:

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package shoot;

import javax.swing.JFrame;

class Main extends Thread{
   
    JFrame frame = new JFrame("Shooter");
   
    public static void main(String[] args){
        Main main = new Main();
        main.init();
       
       
    }
   
    private void init(){
        Thread thread = new Thread(this);
        thread.start();
        Ship ship = new Ship();
        frame.setVisible(true);
        frame.setSize(500, 500);
        frame.getContentPane().add(ship);
        ship.run();
       
    }
   
   
   
}

---

Ship Class:

Code:

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package shoot;

import java.awt.Graphics;


public class Ship extends Controllable{
   
   
   
    @Override public void paintComponent(Graphics g){
        g.fillRect(20, 0, 10, 10);
        g.fillRect(0, 10, 50, 30);
        repaint();
    }

    @Override
    public void move() {
        System.out.print("hello");
    }

   
   
   
}

---

Controllable Class:

Code:

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package shoot;

import java.awt.Graphics;
import javax.swing.JPanel;

public abstract class Controllable extends JPanel implements Runnable{
   
    int sleepTime = 33;
   
    public Controllable(){
       
    }
   
    @Override public void run() {
        while(true){
            try {
                move();
                Thread.sleep(33);
            } catch (InterruptedException ex) {
                System.out.print("Thread in class Controls Interrupted \n  at line 17");
            }
        }
    }
   
    public abstract void move();
   
    public int getSleepTime(){
        return sleepTime;
    }
   
   
    @Override public abstract void paintComponent(Graphics g);
   
   
}

---

Any ideas?

1) NEVER invoke repaint() from within the paintComponent() method. This will cause a loop.

2) Don't use Threads for animation. See: How to Use Swing Timers (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Other Swing Features)

3) Don't use KeyEvents to handle the arrow keys. See: How to Use Key Bindings (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Other Swing Features)

Moved from 'New to Java'

db

Quote:

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Originally Posted by camickr

1) NEVER invoke repaint() from within the paintComponent() method. This will cause a loop.

2) Don't use Threads for animation. See: How to Use Swing Timers (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Other Swing Features)

3) Don't use KeyEvents to handle the arrow keys. See: How to Use Key Bindings (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Other Swing Features)

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Thanks, but that leaves me with another question. What are threads used for?

You use a Thread to execute long running tasks so you don't block the Swing GUI from repainting itself. Read the section from the above tutorial on "Concurrency" which explains more about threads.