keep track of LineNumbers in a JTextarea

[keffie91]

Hello I want to keep track of the LineNumbers of a JTextarea. I know that you can keep track of the LineNumbers in a file by using LineNumberReader.

But I am writing a texteditor and sometimes you want to start a new File and before you safe it I want also be able to write out the LineNumbers.

Does annyone knows if it is possible what I want?

keffie91

[serjant]

Of course it is possible,examine my editor ,which i wrote this year SourceForge.net: Sampad
If you need the source code,tell me.

[Norm]

Trap the append calls and count the newlines as text is added to the text area.
Get the text area's text and count the number of newlines.

[serjant]

i will tell you the idea how i implemented this and also how it is implemented in Eclipse (LineNumber track consists of JPanel and JLabels with numbers):
1.create private class which implements DocumentListener and it extends Thread.

Code:

private class MyDocumentListener extends Thread  implements DocumentListener {
		 public void changedUpdate(DocumentEvent e) {
	        //Plain text components do not fire these events
	          }
		
	    public void insertUpdate(DocumentEvent e) {
               
                    Document doc = (Document)e.getDocument();

2.then you should know every time when you type the rows size of the JTextArea,remember everything in this class(supposing that your JTextArea is tdefined as textArea):

Code:

int rows=textArea.getLineCount();

3.removes evertyhing from your LineNumbers panel (supposing that LineNumber track is JPanel lineNumberPanel):

Code:

lineNumberPanel.removeAll();

4.Add again labels on the line number count panel and repaint it:

Code:

for(int i=1;i<=rows;i++){
	        	JLabel lineCount=new JLabel(""+i);
	        	lineCount.setFont(textArea.getFont());
	        	lineNumberPanel.add(lineCount);
	        	
	        }
               lineNumberPanel.updateUI();
}

5.the same you can do when you remove the line:

Code:

public void removeUpdate(DocumentEvent e) {}

I hope you understood.Welcome

[keffie91]

Ok thanks, but I don't know exactly where to implemt the code where do I have to put all the pieces of the code, In the methods?. And do I have to put the class MydocumentListener in a new file? Because in eclipse it is not possible to create a private class.

thanks keffie91

[serjant]

don't forget to set the size of the line number panel and to adjust the layout to it.And for better performance the color:

Code:

lineNumberPanel.setPreferredSize(new Dimension(15, textArea.getHeight()));
lineNumberPanel.setBackground(Color.gray);
lineNumberPanel.setLayout(new BoxLayout(lineNumberPanel,BoxLayout.Y_AXIS));

[keffie91]

Can you sent me the code of your texteditor, because I don't understand what lines of code i have to put where in my code.

thanks keffie91

[serjant]

I hope you won't spend two weeks on examining my code ,it is 500kb weight.
Give me your email please,remember man it is GPL license.

[keffie91]

Can you maybe tell me where i have to put these lines:

lineNumberPanel.removeAll();
int rows=textArea.getLineCount();

for(int i=1;i<=rows;i++){
JLabel lineCount=new JLabel(""+i);
lineCount.setFont(textArea.getFont());
lineNumberPanel.add(lineCount);

}
lineNumberPanel.updateUI();
}

in the class MyDocumentListener or in the class of my editor?

thanks keffie91

[serjant]

In the class editor create the private class MyDocumentListener which implements DocumentListener and extends Thread ,then add in method
public void insertUpdate(DocumentEvent e) your code.

[keffie91]

Ok that is clear. It is working a bit now. I write out the LineNumbers in a JLabel, but they are written out horizontal. And that is just not what I want. I want them vertical.

I have thought this:
JLabel lineCount= new JLabel( "\n" + i);

\n is the standard character for a new line. But it doesn't work.
Does anyone knows why this is not working?

thanks keffie91

[serjant]

adjust the layout for the lineNumberPanel:

Code:

lineNumberPanel.setLayout(new BoxLayout(lineNumberPanel,BoxLayout.Y_AXIS));

[keffie91]

I tried to think of a method to remove the LineNumbers. But it is not so easy as i thought. Can you give me some hints

thanks keffie91

[serjant]

Have you implemented the adding numbering the lines in the text area?
Ok for removing you should again to create in the same class the method called removeUpdate(Document e) like this:

Code:

 public void removeUpdate(DocumentEvent e) {
	 
	    	
	    	int rows=textArea.getLineCount();
	    	lineNumberPanel.removeAll();
	        for(int i=1;i<=rows;i++){
	        	JLabel lineCount=new JLabel(""+i);
	        	lineCount.setFont(textArea.getFont());
	        	lineNumberPanel.add(lineCount);
	        	
	        	
	        }
	        lineNumberPanel.updateUI();
        	
	        
	    }