Help with actionPerformed Statements

[wco5002]

Hi, I'm creating a small photo album that will read images in from an array. The applet will also have a few buttons (first, previous, next, last), which will allow the user to switch to the next photo. However, I'm a little unsure on how to write the actionPerformed statements to switch the photos, hopefully you guys can give me a few pointers. Here is the code thus far:

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


public class Virtual_Photo_Album extends Applet implements ActionListener
{
    private Image imageArr[] = new Image [5];
    private AudioClip myAudioClip;
    private Button firstButton, previousButton, nextButton, lastButton;
    
    public void init() 
    {
       myAudioClip = getAudioClip(getCodeBase(), "../../audio.au");  // Obtians sound clip.
       myAudioClip.loop();   // Loops the audio clip.
       
           
       imageArr[0] = getImage(getCodeBase(),"../../images/image1.jpg");
       imageArr[1] = getImage(getCodeBase(),"../../images/image2.jpg");
       imageArr[2] = getImage(getCodeBase(),"../../images/image3.jpg");
       imageArr[3] = getImage(getCodeBase(),"../../images/image4.jpg");
       imageArr[4] = getImage(getCodeBase(),"../../images/image5.jpg");
    
        
       firstButton = new Button("First");     // Buttons
       firstButton.addActionListener(this);   // Assigns the ActionListeners
       previousButton = new Button("Previous");
       previousButton.addActionListener(this);
       nextButton = new Button("Next");
       nextButton.addActionListener(this);
       lastButton = new Button("Last");
       lastButton.addActionListener(this);
       
       add(firstButton);
       add(previousButton);
       add(nextButton);
       add(lastButton);
    }
    

        public void paint (Graphics g) 
        {
            g.drawImage(imageArr[0], 0, 0, this);
            g.drawImage(imageArr[1], 0, 0, this);
            g.drawImage(imageArr[2], 0, 0, this);
            g.drawImage(imageArr[3], 0, 0, this);
            g.drawImage(imageArr[4], 0, 0, this);
        }
    
    public void actionPerformed(ActionEvent e)
    {
        
    }
}

[Eranga]

You have to get the correct action command depend on the buttons action listener. Something like this.

    public void actionPerformed(ActionEvent e)
    {
            if("First".equals(event.getActionCommand())){
            // Do the processing here
        }    
    }

[wco5002]

How can I incorporate the repaint() method into this?

Would I have to write something like this:

     public void actionPerformed(ActionEvent e)
     {
          if("firstButton".equals(event.getActionCommand())){
               g.drawImage(imageArr[0], 0, 0, this)
          }
     }

[Eranga]

Did you try it? If so what happened?

[wco5002]

I receive two errors:

C:\Users\William\Virtual_Photo_Album\src\Virtual_P hoto_Album.java:69: cannot find symbol
symbol : variable event
location: class Virtual_Photo_Album
if("firstButton".equals(event.getActionCommand())) {
C:\Users\William\Virtual_Photo_Album\src\Virtual_P hoto_Album.java:70: cannot find symbol
symbol : variable g
location: class Virtual_Photo_Album
g.drawImage(imageArr[0], 0, 0, this);

[Eranga]

You have to change the following code

if("firstButton".equals(event.getActionCommand())){

as

if("firstButton".equals(e.getActionCommand())){

And also how can you call the line

g.drawImage(imageArr[0], 0, 0, this)

with out referring the graphic class. At the same time you have miss the semicolon at the end of that line.

[wco5002]

Ok, I changed it as you stated, here is what I have then:

    public void actionPerformed(ActionEvent e)
    {
          if("firstButton".equals(e.getActionCommand()))
          {
              public void paint (Graphics g)
              {
                  g.drawImage(imageArr[0], 0, 0, this);
              }
          }
     }

But now there are four errors:

C:\Users\William\Virtual_Photo_Album\src\Virtual_P hoto_Album.java:69: illegal start of expression
public void paint (Graphics g)

C:\Users\William\Virtual_Photo_Album\src\Virtual_P hoto_Album.java:69: illegal start of expression
public void paint (Graphics g)

C:\Users\William\Virtual_Photo_Album\src\Virtual_P hoto_Album.java:69: ';' expected
public void paint (Graphics g)

C:\Users\William\Virtual_Photo_Album\src\Virtual_P hoto_Album.java:69: ';' expected
public void paint (Graphics g)

[Eranga]

Yes this is wrong, you can't build a method inside the other. You can call any method within it with correct arguments actually. Just look at last two errors. It outline that after it if condition-loop it expecting statements, not a method.

[Eranga]

Is that you have seen buttons on the applet before adding the actionePerformed() in your code?