One thread starts one does not

Question

hello
still i'm learning threads.
i've got an applet "pingpong".
there are two threads
1. pingThread pt
2. Thread sammelThread
pingthread makes some int-values
sammelThread collects them and repaints the applet.
i've got 2 problems:
1. -- sammelthread does not start
2. -- if paint() gets the right value, (see commented line in paint())it does not repaint the rectangle
the source:
public class pingThread extends Thread{
     private int hoehe = 10;
     private boolean up = true;
     public void run(){
                        while(true){
                                if (isInterrupted()){
                                        break;
                                }//if
                                if (up){
                                        hoehe = hoehe +10;
                                        if (hoehe == 200){
                                                up = false;
                                        }//if
                                }else{
                                        hoehe = hoehe -10;
                                        if (hoehe == 10){
                                                up = true;
                                        }//if
                                }//if-else
                                System.out.println("hoehe/up: " + hoehe + ", " +up);
                                try {
                                        Thread.sleep(400);
                                } catch (InterruptedException e) {
                                        interrupt();
                        }//while
                }//run
                public int gethoehe(){
                        System.out.println(" und nun :  gethoehe() = " +hoehe);
                        return hoehe;
}//class
import java.awt.*;
import java.awt.event.*;
import java.awt.Graphics;
public class pingpong extends java.applet.Applet implements Runnable, ActionListener{
        Button btn;
        pingThread pit = new pingThread();
        Thread sammelThread;
        int pinghoehe;
        public void init() {
                setLayout (new FlowLayout() );
                btn = new Button("Stop");
                btn.addActionListener(this);
                add(btn);
                setVisible(true);
                pit.start();
                repaint();
        }//init()
        public void actionPerformed(ActionEvent event){
        Object obj = event.getSource();
                if (obj == btn){
                        System.out.println("Button : Stop");
                        pit.interrupt();
        }// actionPerformed
        public void paint(Graphics g){
                 //zum testen:
                 //pinghoehe = pit.gethoehe();
                System.out.println("paint - pinghoehe = " +pinghoehe);
                g.fillRect(10,pinghoehe, 5, 5);
        public void start(){
                System.out.println("pingpong - start");
                if (sammelThread == null){
                        sammelThread = new Thread();
                        System.out.println("pingpong - start -start");
                        sammelThread.start();
        }//start
        public void stop(){
                if (sammelThread != null) {
                        sammelThread = null;
        }//stop
        public void run(){
                System.out.println("sammelthread.run()");
                while(true){
                        pinghoehe = pit.gethoehe();
                        System.out.println("sammelthread - pinghoehe = " +pinghoehe);
                        repaint();
                }//while
        }//run
} //pong()

Answer 1

With
sammelThread = new Thread();
sammelThread.start();
you are creating a new Thread, which will do nothing.
If you want to call the run-method of your own Runnable "pingpong" (better with uppercase "Pingpong", because it's a classname!), you have to write:
sammelThread = new Thread(this);
sammelThread.start();
The method start of sammelThread will call the run-method of the Runnable this (pingpong).