Convert Swing class to Applet?

[Kriss Reddy]

Hello,

I am not sure if 'Subject' is correct to this post, if not, sorry for the confusion.

I am new to applets, Swing, AWT.
To start with I took an example and changed as shown below, which works fine if main() is un-commented.

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class FolderTreePanel extends JPanel 
			implements ActionListener {
	
    private static String BROWSE_COMMAND = "browse";
    private static String TRANSFER_COMMAND = "transfer";
    private static String CLEAR_COMMAND = "clear";
    
    JLabel folderPathVal;
    JTextField txt;
    
	public FolderTreePanel() {
		super(new BorderLayout());
		
		JLabel folderPath = new JLabel("Folder Path:");
		folderPathVal = new JLabel();
		txt = new JTextField();

		JButton addButton = new JButton("Browse");
		addButton.setActionCommand(BROWSE_COMMAND);
		addButton.addActionListener(this);

		JButton removeButton = new JButton("Transfer");
		removeButton.setActionCommand(TRANSFER_COMMAND);
		removeButton.addActionListener(this);

		JButton clearButton = new JButton("Clear");
		clearButton.setActionCommand(CLEAR_COMMAND);
		clearButton.addActionListener(this);
		
		JPanel panel = new JPanel();
		panel.setSize(600, 400);
        panel.add(addButton);
        panel.add(removeButton); 
        panel.add(clearButton);
        panel.add(folderPath);
        panel.add(folderPathVal);
        add(panel, BorderLayout.CENTER);
	}
	
	@Override
	public void actionPerformed(ActionEvent e) {
		String command = e.getActionCommand();
        
        if (BROWSE_COMMAND.equals(command)) {
            //Add button clicked
            System.out.println("FolderTreePanel.actionPerformed()1");
            JFileChooser jfc = new JFileChooser();
            jfc.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
            
            int retVal = jfc.showOpenDialog(FolderTreePanel.this);
            if(retVal == JFileChooser.APPROVE_OPTION){
            	folderPathVal.setText(jfc.getSelectedFile().getAbsolutePath());
            }
        } else if (TRANSFER_COMMAND.equals(command)) {
            //Remove button clicked
            System.out.println("FolderTreePanel.actionPerformed()2");
            CreateFiles.createFiless();
        } else if (CLEAR_COMMAND.equals(command)) {
            //Clear button clicked.
            System.out.println("FolderTreePanel.actionPerformed()3");
            if(folderPathVal.getText().length()>0){
            	folderPathVal.setText("");
            }
        }
	}
	
    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("FolderTreePanel");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        FolderTreePanel newContentPane = new FolderTreePanel();
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.setSize(400, 400);
        frame.setVisible(true);
    }
    
//    public static void main(String[] args) {
//        //Schedule a job for the event-dispatching thread:
//        //creating and showing this application's GUI.
//        javax.swing.SwingUtilities.invokeLater(new Runnable() {
//            public void run() {
//                createAndShowGUI();
//            }
//        });
//    }

}

Below listed class is used in the above class.

import java.io.File;
import java.io.IOException;

public class CreateFiles {
	public static void createFiless(){
		for(int i=0; i<10; i++){
			File fil = new File("c:\\temp\\Register" + i + ".txt");
			if(!fil.exists()){
				try {
					fil.createNewFile();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

}

Both classes are working fine.

Now I tried to convert them into an Applet as shown below:

import javax.swing.JApplet;
import javax.swing.SwingUtilities;

public class FolderTreeApplet extends JApplet {
	public void init() {
        //Execute a job on the event-dispatching thread; creating this applet's GUI.
        try {
            SwingUtilities.invokeAndWait(new Runnable() {
                public void run() {
                    createGUI();
                }
            });
        } catch (Exception e) { 
            System.err.println("createGUI didn't complete successfully");
        }
    }
    
    /**
     * Create the GUI. For thread safety, this method should
     * be invoked from the event-dispatching thread.
     */
    private void createGUI() {
        //Create and set up the content pane.
        FolderTreePanel newContentPane = new FolderTreePanel();
        newContentPane.setOpaque(true); 
        setContentPane(newContentPane);        
    }

}

Applet is called on my webpage as shown below:

  
function loadNextPage( )
{
    document.write("<APPLET name='CreateFiles' code='com.java.applets1.FolderTreeApplet.class' archive='CreateFiles.jar'>");
    document.write("</APPLET>");
}
<form>
<input type="button" value="Proceed" size="10" onclick="loadNextPage()">
</form>

 

Applet is loaded on my webpage, but none of the functionality is available for use, ie nothing happens when buttons are clicked. Please tell me where I went wrong.

Thanks,
Kriss.

[Girish Limaye]

Implement the listener interfaces. It might work properly.

[Ulf Dittmer]

So every time you click that button a new applet is created? I would not expect that to work at all, especially as it happens after the page has initially been created. Make the applet a proper part of the page from the beginning, and then call its public methods from JavaScript as necessary; search the FAQ for "LiveConnect" for more information.

[Kriss Reddy]

Hi Girish,
Could you please tell me what those listener interfaces are?

Hi Ulf,

Make the applet a proper part of the page from the beginning

Does that mean, placing applet on the page instead of calling from javascript, as shown below?

 
<APPLET name='CreateFiles' code='com.java.applets1.FolderTreeApplet.class' archive='CreateFiles.jar'>
</Applet>   

I placed the applet on the page, applet is loaded properly but none of the buttons worked.

Thanks.

[Ulf Dittmer]

Yes, that's what I meant.

I placed the applet on the page, applet is loaded properly but none of the buttons worked.

Have you considered investigating why that is, instead of trying to running the applet in a much more convoluted way?