I want to know the column number and row number where the cursor in JTextArea. ie. in notepad when i m at first line than status bar shows Ln 1, Col 1.
thanks in advance...
Here is the code
import java.awt.BorderLayout;
import javax.swing.*;
import javax.swing.event.*;
public class caretDemo extends JFrame {
// Two controls, one is the editor and the other is our little status bar at the bottom.
// When we update the editor, the change in caret will update the status text field.
private JTextArea editor;
private JTextField status;
// Start of our caretDemo class
public caretDemo() {
setTitle("Caret Demo");
setSize(500,500);
// Lets create a border layout to make positioning of items easy and quick.
setLayout(new BorderLayout());
setDefaultCloseOperation(EXIT_ON_CLOSE);
editor = new JTextArea();
// Add a caretListener to the editor. This is an anonymous class because it is inline and has no specific name.
editor.addCaretListener(new CaretListener() {
// Each time the caret is moved, it will trigger the listener and its method caretUpdate.
// It will then pass the event to the update method including the source of the event (which is our textarea control)
public void caretUpdate(CaretEvent e) {
JTextArea editArea = (JTextArea)e.getSource();
// Lets start with some default values for the line and column.
int linenum = 1;
int columnnum = 1;
// We create a try catch to catch any exceptions. We will simply ignore such an error for our demonstration.
try {
// First we find the position of the caret. This is the number of where the caret is in relation to the start of the JTextArea
// in the upper left corner. We use this position to find offset values (eg what line we are on for the given position as well as
// what position that line starts on.
int caretpos = editArea.getCaretPosition();
linenum = editArea.getLineOfOffset(caretpos);
// We subtract the offset of where our line starts from the overall caret position.
// So lets say that we are on line 5 and that line starts at caret position 100, if our caret position is currently 106
// we know that we must be on column 6 of line 5.
columnnum = caretpos - editArea.getLineStartOffset(linenum);
// We have to add one here because line numbers start at 0 for getLineOfOffset and we want it to start at 1 for display.
linenum += 1;
}
catch(Exception ex) { }
// Once we know the position of the line and the column, pass it to a helper function for updating the status bar.
updateStatus(linenum, columnnum);
}
});
// Add the fields to the layout, the editor in the middle and the status at the bottom.
add(editor, BorderLayout.CENTER);
status = new JTextField();
add(status, BorderLayout.SOUTH);
// Give the status update value
updateStatus(1,1);
}
// This helper function updates the status bar with the line number and column number.
private void updateStatus(int linenumber, int columnnumber) {
status.setText("Line: " + linenumber + " Column: " + columnnumber);
}
// Entry point to the program. It kicks off by creating an instance of our class and making it visible.
public static void main(String args[]) {
caretDemo caretDemoApp = new caretDemo();
caretDemoApp.setVisible(true);
}
}
Output
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