Help with JList and TextArea...

[gabrielle_l]

So far my app has an empty jlist and it can also open a file and display it in the text area. I want my app to do the following: when u click on different elements in the jlist, they display different things in the text area. The text area should come from a file in the computer. So when you open a file and display in the text area, i want to save it as an element in the list, that can be displayed again when that element is selected. does anyone have any ideas, im really struggling...

[so1i]

What code have you got so far?

[gabrielle_l]

so far my code can add element to list with the save button and can open file to the text area, but i dont know how to associate the element to the contents of the text area. code is below:

[Stu_328]

Here try something like this:

When you open the file for the first time:

					//Add it to the list
					listModel.addElement(newFile);
					TestMain.this.validate();

Then something like this when you click the list:

		list.addListSelectionListener(new ListSelectionListener(){
			@Override
			public void valueChanged(ListSelectionEvent e) {
				File file = null;
				if(list.getSelectedValue() instanceof File)
					file = (File)list.getSelectedValue();
				else
					return;

				BufferedReader bReader = null;
				try {
					bReader  = new BufferedReader( new InputStreamReader( new FileInputStream(file) ) ) ;
					String read;  
					StringBuffer text = new StringBuffer() ;  
					while( (read = bReader.readLine() ) != null )   
					{  
						text.append( read ).append( "\n" ) ;  
					}  
					textArea.setText( text.toString() ) ; 
				} catch (Exception e1) {
					e1.printStackTrace();
				} finally{
					try{
						bReader.close();
					}catch(Exception ex){ex.printStackTrace();}
				}
				TestMain.this.validate();
			}
		});

Where <TestMain> is the name of your class.

You might need to make your own object if you want to display other stuff in the text area...

HTH

[gabrielle_l]

Thanks this works great, it displays the file path in the jlist as the item, and the listener works how i wanted it to. One further question: if i wanted to have a custom name for the jlist item (from an input dialog) will it still work, because i have been trying to do this.

The naming of the item will come from:

String textName = JOptionPane.showInputDialog(null, "Graph Name : ");
				if(textName != null){
					
					System.out.println(textName);
					
			         }
			        else
			        	JOptionPane.showMessageDialog(null, "You pressed cancel button.");

when you open the file:

String newFile = textName;
listModel.addElement(newFile);
test.this.validate();

This code renames the jlist items correctly but then the listener doesnt work and the textarea doesnt change, have you got any more suggestions. thanks.

[Stu_328]

The list is a list of File objects not Strings. Your adding the String (ie the path of the file), to the list.

In the listener code, if you look, there's this:

if(list.getSelectedValue() instanceof File)
 file = (File)list.getSelectedValue();
else
 return;

This is using the instanceof keyword. If you haven't encountered it before, look it up or ask here.

It checks to see if the selected item is a File and only if its a file will the proceed. Otherwise it returns.
So when it finds your String that you added it just returns because it fails the test to see if it's a file.

So, what do you think you need to do to resolve?