Need help to map KeyStrokes in ActionMap using CardLayout in a JApplet

**bugemberuth** · January 10th, 2014, 12:47 PM

Hi guys. Thanks for your time. Can someone please give a code that maps arrow key KeyStrokes of an ActionMap in AnyClass which extends a JPanel the arrow keys moves a ball in AnyClass

AnyClass is called in a CardLayoutClass and CardLayoutClass is called in a JApplet.

I am sorry I cannot post the code because the system says it is my first post and something to do with spam.

Thanks again for your time

Ruth Bugembe

**andbin** · January 10th, 2014, 03:13 PM

Originally Posted by bugemberuth

Can someone please give a code that maps arrow key KeyStrokes of an ActionMap in AnyClass which extends a JPanel the arrow keys moves a ball in AnyClass

Just one question: why do you need to go at the deep level of input/action maps? What's wrong with a basical KeyListener?

**GregBrannon** · January 10th, 2014, 04:45 PM

Welcome to the forum! Please read this topic to learn how to post code in code or highlight tags and other useful info for newcomers.

**bugemberuth** · January 11th, 2014, 06:31 AM

Thank you andbin thanks for ur time but am no gui expert. I read some where that KeyListener are wore difficult to manage. I need to use the arrow keys in a game I am hosting at Home as an alternative to pressing the buttons. Below is the code that tries to explain what I want to do but failing

package keymapingincardlayout;
 
import java.applet.Applet;
 
import java.awt.BorderLayout;
import java.lang.reflect.InvocationTargetException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 *
 * @author Administrator
 */
@SuppressWarnings("serial")
public class AppletClass extends javax.swing.JApplet{
 
    static CardlayoutClass cardLayoutClass; 
 
	@Override
   @SuppressWarnings("static-access")
	public void init(){
           resize(900, 550); 
             cardLayoutClass = new CardlayoutClass();
 
       try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                    @Override
                    public void run(){
                        getContentPane().add(cardLayoutClass.getMainPanel(), BorderLayout.CENTER);
                        cardLayoutClass.showAnyClass();                      
                    }
            });
        } catch (InterruptedException | InvocationTargetException ex) {
            //<editor-fold defaultstate="collapsed" desc="comment">
 
            //</editor-fold>
         Logger.getLogger(AppletClass.class.getName()).log(Level.SEVERE, null, ex);
        }
     }
}
 
 
package keymapingincardlayout;
 
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JPanel;
 
/**
 Calls AnyClass
 */
class CardlayoutClass {
    static JPanel mainPanel;
    private static JPanel anyClassPanel;
 
    private static AnyClass anyClass;
    private static CardLayout cardLayout = new CardLayout();
    CardlayoutClass()
    {
        mainPanel = new JPanel();
 
        mainPanel.setLayout(cardLayout);
        mainPanel.setPreferredSize(new Dimension(900,550));
        mainPanel.setBackground(Color.blue);       
    }
    /*
     * called by the AppletClass
     */
     public static void showAnyClass()
    {
        anyClassPanel  = new JPanel();
        anyClassPanel.setPreferredSize(new Dimension(500, 500));
 
        anyClass = new AnyClass();           
        anyClassPanel.add(anyClass);
 
        mainPanel.add(anyClassPanel, "anyClas");
        cardLayout.show(mainPanel, "anyClass");
 
        anyClassPanel.setFocusable(true);
        anyClassPanel.requestFocusInWindow();
 
    } 
    /*
     * called by the AppletClass
     */
     public static JPanel getMainPanel()
     {
         return mainPanel;
     }       
}
 
 
package keymapingincardlayout;
 
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
 
/**
Calls Ball
 */
class AnyClass extends JPanel{
    static  InputMap inputMap;
    static ActionMap actionMap;
    static Ball ball;   
 
    AnyClass()
    {
        setPreferredSize(new Dimension(500, 500));
        setLayout(new FlowLayout(FlowLayout.CENTER));
        setBackground(Color.red);
        createBall();
 
        inputMap = getInputMap();
        actionMap = getActionMap();
        mapKeysToBall();
        setActionMap(actionMap);
        setInputMap(JComponent.WHEN_FOCUSED, inputMap);      
    }
 
      public void paintComponent(Graphics g) {
 
            super.paintComponent(g);          
            ball.drawMyBall(g);                  
        }
      private void createBall() {          
        ball = new Ball(240, 240, 50, 50); 
    } 
 
//Moves myBall to the right
    public void turnRight() {
        ball.moveRight();
        repaint();
    }
 
    //Moves myBall to the left
    public void turnLeft() {
        ball.moveLeft();
        repaint();
    }
 
    //Moves myBall down
    public void turnSouth() {
        ball.moveDown();
        repaint();
    }
 
    //Moves myBall up
    public void turnNorth() {
        ball.moveUp();
        repaint();
    }
 
    void mapKeysToBall()
    {
        System.out.println("Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "moveright");      	                                          
        actionMap.put("moveright", rightAction);
 
        System.out.println("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "moveLeft");      	                                           
        actionMap.put("moveLeft", leftAction);
 
        System.out.println("ccccccccccccccccccccccccccccccccccc");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "moveUp");      	                                          
        actionMap.put("moveUp", upAction);
        System.out.println("dddddddddddddddddddddddddddddddddddddddd");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "moveDown");      	                                         
        actionMap.put("moveDown", downAction);
        System.out.println("eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee");
        //setActionMap(actionMap);
        System.out.println("fffffffffffffffffffffffffffffff");
 
    }
      private AbstractAction rightAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("111111111111111111111111111111111111");
            turnRight();
 
        }
        }; 
 
       private AbstractAction leftAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("22222222222222222222222222222222222222222");
          turnLeft();
        }
        };
 
       private AbstractAction upAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("333333333333333333333333333333333333333333");
            turnNorth();
        }
        };
 
       private AbstractAction downAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("4444444444444444444444444444");
            turnSouth();
        }
        };   
 
}
 
 
package keymapingincardlayout;
 
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
 
class Ball  extends JPanel{
    int myX;
    static int myY;
    static int xDiameter;
    static int yDiameter;
    static int step;
 
    Ball(int x, int y, int xdmtr, int ydmtr)
    {
        myX = x;
        myY = y;
        xDiameter = xdmtr;
        yDiameter = ydmtr; 
         step = 14;        
    }
 
    /*
     *Moves the player's ball left
     */
    public void moveLeft()
    {
        myX -= step;
    }
 
    /*
     *Moves the player's ball right
     */
    public void moveRight() 
    {
        myX += step;
    }
 
    /*
     *moves the player's ball up
     */
    public void moveUp()
    {
        myY -= step;
    } 
    /*
     *Moves the player's ball down
     */
    public void moveDown() 
    {
        myY += step;
    }
    public void drawMyBall(Graphics g) {
        g.setColor(Color.white);
        g.fillOval(myX, myY, xDiameter, yDiameter);
 
    }
   }

**andbin** · January 11th, 2014, 09:38 AM

Originally Posted by bugemberuth

Below is the code that tries to explain what I want to do but failing

In your code, movements works (not all correctly, review the code), but you have to give manually the focus. With your code I need to use the TAB key to reach the focusable panel.

This is because you have done:

anyClassPanel.requestFocusInWindow();

while you should do

anyClass.requestFocusInWindow();

And apart this, your code is very "smoky", twisted and full of mistakes and inappropriate things. You have used many class (static) variables, which are not appropriate in your case. Then it's not necessary that Ball extends JPanel (you are not using Ball as a "component").
The use of input/action maps give, as result, a more long and complex code. More long than using a simple KeyListener.
And there are other bad/inappropriate things that I don't mention now just to avoid a long post .....

**bugemberuth** · January 11th, 2014, 04:14 PM

Hi andbin

Thank you very much. The code I sent you has worked. Thanks for your time. Ido not know when I transfer it to my project it does not work. I am going to try find out what is wrong. as for KeyListener, I am going to look at it. Gui is new to me

Ruth

**bugemberuth** · January 12th, 2014, 08:32 AM

Hi Andrea

I appreciate the help you have so far given me but I have failed to work my way round about this problem. As stated above the code you gave me works fine. but when I Incorporated it in my project it failes. i believe this has something to do with calling the CardLayoutClass is called more than once. In my project it is called 4 times before the Maze (AnyClass) is displayed. Below is the new code I have put MiddleClass which calls AnyClass. I need to take time to study the KeyListener I am using static variables because I am doing alot of class referencing guess due bad project design

 
package keymapingincardlayout;
 
import java.applet.Applet;
 
import java.awt.BorderLayout;
import java.lang.reflect.InvocationTargetException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 *
 * @author Administrator
 */
@SuppressWarnings("serial")
public class AppletClass extends javax.swing.JApplet{
 
    static CardlayoutClass cardLayoutClass; 
 
	@Override
   @SuppressWarnings("static-access")
	public void init(){
           resize(900, 550); 
             cardLayoutClass = new CardlayoutClass();
 
       try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                    @Override
                    public void run(){
                        getContentPane().add(cardLayoutClass.getMainPanel(), BorderLayout.CENTER);
                        cardLayoutClass.showMiddleClass();
                        //cardLayoutClass.showAnyClass(); 
                    }
            });
        } catch (InterruptedException | InvocationTargetException ex) {
            //<editor-fold defaultstate="collapsed" desc="comment">
 
            //</editor-fold>
         Logger.getLogger(AppletClass.class.getName()).log(Level.SEVERE, null, ex);
        }
     }
}
 
package keymapingincardlayout;
 
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JPanel;
 
/**
 Calls AnyClass
 */
class CardlayoutClass {
    static JPanel mainPanel;
    private static JPanel middleClassPanel;
    private static JPanel anyClassPanel;
 
    private static MiddleClass middleClass;
    private static AnyClass anyClass;
    private static CardLayout cardLayout = new CardLayout();
    CardlayoutClass()
    {
        mainPanel = new JPanel();
        mainPanel.setLayout(cardLayout);
        anyClassPanel  = new JPanel();
        middleClassPanel  = new JPanel();
 
        mainPanel.add(middleClassPanel, "middle");
 
 
        mainPanel.setPreferredSize(new Dimension(900,550));
        mainPanel.setBackground(Color.blue);       
    }
    /*
     * called by the AppletClass
     */
     public static void showAnyClass()
    {
        anyClassPanel  = new JPanel();
       anyClassPanel.setPreferredSize(new Dimension(500, 500)); 
       anyClass = new AnyClass();
       anyClassPanel.add(anyClass); 
 
        mainPanel.add(anyClassPanel, "startClass");
        cardLayout.show(mainPanel, "startClass");      
 
    } 
 
     public static void showMiddleClass()
    {
        middleClassPanel.setPreferredSize(new Dimension(500, 500));
 
        middleClass = new MiddleClass();;       
        middleClassPanel.add(middleClass);
 
 
        cardLayout.show(mainPanel, "middle");
        System.out.println("MiddleClass");
 
    }     
    /*
     * called by the AppletClass
     */
     public static JPanel getMainPanel()
     {
         return mainPanel;
     }       
}
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JPanel;
 
/**
 *
 * @author Administrator
 */
class MiddleClass extends JPanel{
   private static JButton callsAnyClass;
    MiddleClass()
    {
        setPreferredSize(new Dimension(500, 500));
        setLayout(new FlowLayout(FlowLayout.CENTER));       
        setBackground(Color.green);
        add(createCallsAnyClass());
    }
 
    private static JButton createCallsAnyClass()
    {
       callsAnyClass = new JButton("Call AnyClass");
 
       callsAnyClass.setForeground(Color.red);
       callsAnyClass.setBackground(Color.white);
      callsAnyClass.setFont(new Font("sansserif", Font.BOLD, 42));
 
      callsAnyClass.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
         System.out.println("??????????????????????????");
         CardlayoutClass.showAnyClass(); 
      }
  });
  return callsAnyClass;
 
  }
 
}
 
 
package keymapingincardlayout;
 
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
 
/**
Calls Ball
 */
class AnyClass extends JPanel{
    static  InputMap inputMap;
    static ActionMap actionMap;
    static Ball ball;   
 
    AnyClass()
    {
        setPreferredSize(new Dimension(500, 500));
        setLayout(new FlowLayout(FlowLayout.CENTER));
        setBackground(Color.red);
        createBall();
 
        inputMap = getInputMap();
        actionMap = getActionMap();
        mapKeysToBall();
        setActionMap(actionMap);
        setInputMap(JComponent.WHEN_FOCUSED, inputMap);      
    }
 
      public void paintComponent(Graphics g) {
 
            super.paintComponent(g);          
            ball.drawMyBall(g);                  
        }
      private void createBall() {          
        ball = new Ball(240, 240, 50, 50); 
    } 
 
//Moves myBall to the right
    public void turnRight() {
        ball.moveRight();
        repaint();
    }
 
    //Moves myBall to the left
    public void turnLeft() {
        ball.moveLeft();
        repaint();
    }
 
    //Moves myBall down
    public void turnSouth() {
        ball.moveDown();
        repaint();
    }
 
    //Moves myBall up
    public void turnNorth() {
        ball.moveUp();
        repaint();
    }
 
    void mapKeysToBall()
    {
        System.out.println("Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "moveright");      	                                          
        actionMap.put("moveright", rightAction);
 
        System.out.println("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "moveLeft");      	                                           
        actionMap.put("moveLeft", leftAction);
 
        System.out.println("ccccccccccccccccccccccccccccccccccc");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "moveUp");      	                                          
        actionMap.put("moveUp", upAction);
        System.out.println("dddddddddddddddddddddddddddddddddddddddd");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "moveDown");      	                                         
        actionMap.put("moveDown", downAction);
        System.out.println("eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee");
        //setActionMap(actionMap);
        System.out.println("fffffffffffffffffffffffffffffff");
 
    }
      private AbstractAction rightAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("111111111111111111111111111111111111");
            turnRight();
 
        }
        }; 
 
       private AbstractAction leftAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("22222222222222222222222222222222222222222");
          turnLeft();
        }
        };
 
       private AbstractAction upAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("333333333333333333333333333333333333333333");
            turnNorth();
        }
        };
 
       private AbstractAction downAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            System.out.println("4444444444444444444444444444");
            turnSouth();
        }
        };   
 
}
 
 
 
package keymapingincardlayout;
 
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
 
class Ball  extends JPanel{
    int myX;
    static int myY;
    static int xDiameter;
    static int yDiameter;
    static int step;
 
    Ball(int x, int y, int xdmtr, int ydmtr)
    {
        myX = x;
        myY = y;
        xDiameter = xdmtr;
        yDiameter = ydmtr; 
         step = 14;        
    }
 
    /*
     *Moves the player's ball left
     */
    public void moveLeft()
    {
        myX -= step;
    }
 
    /*
     *Moves the player's ball right
     */
    public void moveRight() 
    {
        myX += step;
    }
 
    /*
     *moves the player's ball up
     */
    public void moveUp()
    {
        myY -= step;
    } 
    /*
     *Moves the player's ball down
     */
    public void moveDown() 
    {
        myY += step;
    }
    public void drawMyBall(Graphics g) {
        g.setColor(Color.white);
        g.fillOval(myX, myY, xDiameter, yDiameter);
 
    }
   }

Thanks you very much

**andbin** · January 13th, 2014, 04:45 PM

Originally Posted by bugemberuth

I appreciate the help you have so far given me but I have failed to work my way round about this problem. As stated above the code you gave me works fine. but when I Incorporated it in my project it failes. i believe this has something to do with calling the CardLayoutClass is called more than once. In my project it is called 4 times before the Maze (AnyClass) is displayed. Below is the new code I have put MiddleClass which calls AnyClass. I need to take time to study the KeyListener I am using static variables because I am doing alot of class referencing guess due bad project design

Sorry, I can't understand the difficulty you are having, because I can assure you that things are really more simple than your complex, twisted and smoky code.
Even after my previous conceptual advices, it seems you have not understood and your last code doesn't show any effective improvement.

The Ball class

It's quite correct but with some notes to do:
1) It doesn't need to extend JPanel. I repeat: you are not using Ball as a "component" (and it is not to be used as such!).
2) It should have instance variables ... not "class" (static) variables! And note: these should be private.
3) Fix also the namings in order to follow "good" naming conventions. Don't invent parameter names that differ from the fields!

The PaintPanel class

I name this "PaintPanel", you can name it as you want, AnyClass, MyPainter, BallPainter ... anything you want.
The PaintPanel should have:

1) A public constructor that does (at least) the following things:
- set the panel as "focusable" (this is required to have the focus).
- create a Ball instance.
- register a KeyListener on the panel itself. In the keyPressed method it's sufficient to inspect the KeyEvent to check which key was pressed. Depending on the key, you: 1) invoke the appropriate moveXyz method on Ball and 2) invoke a repaint(). Nothing else.
- [Optional] any visual/graphical settings: background color, borders, preferred size (if the panel is added in a layout that respects the preferred size).

Note 1: the KeyListener should be implemented in this PaintPanel, directly in the class (class PaintPanel implements KeyListener) or as an "anonymous" inner class or as a "regular" inner class. It doesn't mind really, these are more "design" choices that doesn't change the final result.

Note 2: a layout manager like FlowLayout is not necessary: you are not adding components into this panel. This panel is not used as a "container" for other components.

2) Instance variables (not "class", static variables!) at least for the Ball instance.

3) paintComponent is ok. It invokes super.paintComponent and then the drawMyBall on the ball.

Nothing else is really required. This is the "core" that is the bare minimum to create a user-controllable ball.

Everything else you create around this (putting all this in an applet, or a JFrame, using a CardLayout for any other reasons, etc...) is absolutely "extra" and doesn't change this "core" part. The only notable thing: you have to give the focus to PaintPanel. This can be done into PaintPanel or in some external class. It doesn't mind, it's just sufficient to do this somewhere.

If after these further advices you can't make real progresses ..... sorry, I don't know how I can help you more than this .....

**bugemberuth** · January 23rd, 2014, 10:59 AM

Thank you everybody for taking your time to look at my code - very "complex, twisted and smoky code". i am not a very good programmer. I have found out the solution to my problem. It has nothing to do with Key Mapping or Key Listener. It something to do with Cardlayout or Focus_Cycle inside one Container. Well am no expert but it solved my problem

below is the magic code;

     EventQueue.invokeLater(new Runnable() {
 
        @Override
        public void run() {
 
            myPanelThatHoldsTheGraphicsInCardLayoutClass.getComponent(indexOfTheGraphicsInstance).requestFocus();
            //i.e mainPanel.getComponent(0).requestFocus();
        }
    });

**andbin** · January 23rd, 2014, 11:28 AM

Originally Posted by bugemberuth

It something to do with Cardlayout

"focus" has, directly and by itself, nothing to do with a layout manager.

Originally Posted by bugemberuth

below is the magic code;

            myPanelThatHoldsTheGraphicsInCardLayoutClass.getComponent(indexOfTheGraphicsInstance).requestFocus();
            //i.e mainPanel.getComponent(0).requestFocus();

Sorry ... there's no "magic" ..... just only the same "twisted" code!

12 days ago (my answer #5) I told you to use:

anyClass.requestFocusInWindow();

And eventually, it's also possible to put the requestFocusInWindow into the AnyClass constructor:

AnyClass() {
    ..........
    requestFocusInWindow();
}

So ... what is (was) the difficulty about this?

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