how to stop and start bouncing ball in java

Question

I was just wondering how I could manipulate buttons in java to make a bouncing ball stop, and then start. I tried writing an if else statement with a command to start the thread, and a command to stop it. However, that did not work. Could anyone possibly help me? Here is my code:

package javaapplication1;

import java.awt.*;
import java.applet.*;
import java.applet.Applet;
import java.awt.event.*;

public class BouncingBallOriginal extends Applet implements Runnable, ActionListener
{
    Thread t=new Thread(this); /* declare and initialize a new thread */
    int x = 0;
    int y = 0;
   
    int countX = 0;
    int countY = 0;
          
    Button button1;           //space bar
    Button button2;

    public void init()
    {
        setSize(600,350);
        t.start(); /* starts the thread */
 
        setBackground(Color.blue);
       
        button1 = new Button("Button 1");
        add(button1);
        button1.addActionListener(this);

        button2 = new Button("Button 2");
        add(button2);
        button2.addActionListener(this);
    }

    private void incrementX()  { x += 10;  }
    private void decrementX()  { x -= 10;  }
    private void incrementY()  { y += 10;  }
    private void decrementY()  { y -= 10;  }
   
    public void run()
    {
        try
        {
            for(int i = 1; i > 0; i++)
            {
                Thread.sleep(200);
                repaint();
            }
        }
        catch(InterruptedException e)
        {
            //do nothing!
        }
    }
  
    public void actionPerformed(ActionEvent e)
    {
        if (e.getSource() == button1) 
        {
            System.out.println("Button 1 was pressed");
        } 
        else
        {
            System.out.println("Button 2 was pressed");
        }  
    }


    public void paint(Graphics g)
    {
        g.setColor(Color.yellow);
        g.fillOval(x, y, 20, 20);
     
        if(countX< (getSize().width / 10) - 1)
        {
            incrementX();
            countX++;            
        }

        if(countX >= (getSize().width / 10) - 1)
        {
            decrementX();
            countX++;
        }

        if(countX >= (getSize().width / 5) - 2)
        {
            countX=0;
        }

        if(countY < (getSize().height / 10) - 1)
        {
            incrementY();
            countY++;
        }

        if(countY >= (getSize().height / 10) - 1)
        {
            decrementY();
            countY++;
        }

        if(countY >= (getSize().height / 5) - 2)
        {
            countY=0;
        }
    }
}

duplicate? http://stackoverflow.com/questions/16758346/how-pause-and-then-resume-a-thread — rleir, May 12 '16 at 15:28

score 0 · Answer 1 · answered May 12 '16 at 15:55

a way that you can do this is

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;

public class BallControl extends JPanel {
  private Ball ball = new Ball();
  private JButton jbtSuspend = new JButton("Suspend");
  private JButton jbtResume = new JButton("Resume");
  private JScrollBar jsbDelay = new JScrollBar();

  public BallControl() {
    // Group buttons in a panel
    JPanel panel = new JPanel();
    panel.add(jbtSuspend);
    panel.add(jbtResume);

    // Add ball and buttons to the panel
    ball.setBorder(new javax.swing.border.LineBorder(Color.red));
    jsbDelay.setOrientation(JScrollBar.HORIZONTAL);
    ball.setDelay(jsbDelay.getMaximum());
    setLayout(new BorderLayout());
    add(jsbDelay, BorderLayout.NORTH);
    add(ball, BorderLayout.CENTER);
    add(panel, BorderLayout.SOUTH);

    // Register listeners
    jbtSuspend.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        ball.suspend();
      }
    });
    jbtResume.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        ball.resume();
      }
    });
    jsbDelay.addAdjustmentListener(new AdjustmentListener() {
      public void adjustmentValueChanged(AdjustmentEvent e) {
        ball.setDelay(jsbDelay.getMaximum() - e.getValue());
      }
    });
  }
}

score 0 · Answer 2 · answered May 12 '16 at 16:36

Forget about thread if you are talking about moving your objects. You moving your ball by changing its positions by a certain value lets call it speed. The way you should stop your ball is setting its speed to zero when a key is pressed instead of stopping the thread.

how to stop and start bouncing ball in java

2 Answers2