Help implementing DefaultListCellRenderer.

I need help implementing a ListCellRenderer such that based on weather or not a particular value exists within an individual list item, that particular row should be colored.

I create a JList as follows, set the Cell Renderer, I also add a mouse listener and then I add the list to a JScrollPane

I then do the following to populate the JList.

So now I want to check the 8th list item value for each list item to see if it contains the value "Yes"

I make an attempt to use a DefaultListCellRenderer but I am not quite sure how to use it to do what I want.

Currently I get no errors but the list displays garbled information and none of the list items are being colored.

You're passing the JList as the value parameter to the super implementation. What you see is the toString() output of the JList.

Passing 8 as the index parameter isn't correct either.

Thanks for the reply. I relize that I am doing this wrong. I was looking for an example of how to implement this correctly.

Take a break, think about it some, then try again.

I am still not there yet but I feel like I am getting close. Here is my new CellRenderer class. Currently all list items are still not colored.

Yes, you're much closer, but you do need to use consistent indents in your code so that the nesting of loops and conditional blocks can be clearly seen. Refer to http://www.oracle.com/technetwork/java/codeconvtoc-136057.html

Why do you think you need to loop over all the items inside that method? The method will be called by the Swing core code for each index, in order to obtain the renderer for that cell.

Never use == to compare Strings, always use .equals.

Ok so I have cleaned up the class a little but still no luck.

worked OK for me --> changed the text color to red.

Your list is populated with objects of type MusicRecording. Can the item being rendered (the value parameter) ever be equal to the String "Rare"?

Well, attached is a sample output. As you can see in this example, there are two items in the list. They are being pulled in from an Oracle DB. Looking at the first list item, the second value is "Rare". So for this list item and all future list items where the second value is "Rare", is when I want to assign a different foreground color.

OK, so I got it working for th evalue "Rare" and also for the value "true" as seen in the syntax below. However, I would like to have it so that the value "true" is passed to the JList but not actually displayed. Currently it is part of my toString() method. Is there a way to have a value on the list but not actually display it?

The Music Recording Class containing the toString()

public class MusicRecording extends Recording {

/**
	 *  Data members
	 */
	private String artist;
	private int year;
	private String gameDescr;
	private boolean owned;
	private String link;
	private int id;

/**
	 *  Creates a MusicRecording object with given parameter values
	 *  This version creates a MusicRecording w/ an empty duration
	 *
	 */
	public MusicRecording(int theRecordingID,String theArtist, String theGameDescr,
						  String theTitle, 
						  String theCategory, String theImageName, int theYear,boolean theOwned, String theLink) {

super(theTitle, theCategory, theImageName);

artist = theArtist;
		year = theYear;
		gameDescr = theGameDescr;
		owned = theOwned;
		link = theLink;
		id = theRecordingID;
		
	}

public String getArtist() {
		return artist;
	}
	
	public int getID(){
		return id;
	}

public String getDescr(){
		return gameDescr;
	}
	
	public int getYear(){
		return year;
	}
	
//	public void setOwned(boolean theOwned){
//		owned = theOwned;
//	}
	
	public boolean getOwned(){
		return owned;
	}
	
	public String getLink(){
		return link;
		
	}

/**
	 *  Returns the recording running time.
	 *  Overrides the method from Recording.
	 *
	 *  Iterates over the list of tracks and keeps a running
	 *  total of each track's duration.
	 */
	
	/**
	 *  Returns the artist name, title of recording
	 */
	public String toString() {

//display the Name of the Game and other info
		return getTitle() + "," + "   " + getArtist() + "," + "   " + getYear() + "," + "   " + getOwned();
	}

/**
	 *  Allow us to sort the recordings by artist name
	 */
	public int compareTo(Object object) {

MusicRecording recording = (MusicRecording) object;
		String targetArtist = recording.getArtist();

return artist.compareTo(targetArtist);
	}

}

Matthew Fierro wrote:Is there a way to have a value on the list but not actually display it?

Sure there is! Your list is populated with instances of MusicRecording, and those instances are available in the renderer method as the value parameter. After casting value to MusicRecording, you can call any method of the class.

The displayed String defaults to the one returned by toString(), but there's no reason a custom renderer shouldn't use any other String, normally but not compulsorily obtained from value

I am not sure what you mean by

After casting value to MusicRecording, you can call any method of the class.

Currenty I am doing

ArrayList<MusicRecording> info = myDataAccessor.getRecordings(category);

musicListBox.setListData(info.toArray());

Thank You Very Much. It is working beutifully now.

What I do after that is even better. When they click on the item, a new JPanel opens. On it is an embeded VLC player which streams youtube videos. It pulls the link from my Oracle database and stream the video on the screen. I also have a description in a JTextArea which is populated from a text file. Here it is attached.

Sorry to "re-open" this but there is something else I would like to do. If the list is empty, I would like to display an image centered within the JList. I have tried some things below but it is not working.

I added the following to MyListRenderer class.

In my actionListener I do the following.

class GoActionListener implements ActionListener {
		public void actionPerformed(ActionEvent event) {

musicListBox.setCellRenderer(new MyListRenderer());
			
			
			// Get the selected category from the "categoryComboBox"
		    String category = (String) categoryComboBox.getSelectedItem();
		
		
		    
		    
			// Get the recordings
		    ArrayList<MusicRecording> info = myDataAccessor.getRecordings(category);

// Populate the list box
		  
            
		    size = musicListBox.getModel().getSize();
		    		    
		    Icon snesIcon = new ImageIcon("C:\\users\\mfierro\\Desktop\\u2_bestof.gif");
			
		    JList imageList = new JList();
		    
			JLabel snesLabel = new JLabel(snesIcon,JLabel.CENTER);
			
			JPanel snesPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
			
			snesPanel.add(snesLabel);
			
			Object[] panels = {snesPanel};
			
			if(size == 0){
			musicScrollPane.remove(musicListBox);
			musicScrollPane.add(imageList);	
			
			imageList.setListData(panels);
			}
			else{
			musicScrollPane.remove(imageList);	
			musicScrollPane.add(musicListBox);
			musicListBox.setListData(info.toArray());
			}  
				  
		}
	
	}

Essentially what I am trying to do is if the list is empty I want to remove that list since it holds MusicRecording objects and I want to add a new list that holds images. Of course if a selection is made where there is data, I want to remove the image list and put of the list with the data items from the Music Recording.

JList (in a JScrollPane) and JLabel (with an ImageIcon) in a CardLayout