NawaMan's Blog

In Java, JTextComponent (such as JTextArea or JTextPane) can be set to read-only using JTextComponent.setEditable(false) which works fine but there is side effect – the caret is missing. Having the caret around in the read-only text component can be useful as the user can navigate around and use shift key to select the text using keyboard. Here is the code:

import javax.swing.plaf.UIResource;
import javax.swing.text.DefaultCaret;

/**
 * This class is a copy of javax.swing.text.DefaultCaret I only change it to allow it to be display in the
 * non-editable text component
 */
public class NonEditableTextComponentCaret extends DefaultCaret implements UIResource {

	boolean blindOff = false;

    /** Constructs a NonEditableTextComponent caret. */
    public NonEditableTextComponentCaret() {
    	super();

    	final NonEditableTextComponentCaret This = this;

		// Create a new one
		(new Thread() {
			/**{@inheritDoc}*/ @Override
			public void run() {
				while(true) {
					try { Thread.sleep(500); }
					catch(InterruptedException IE) { break; }
					This.blindOff = !This.blindOff;
					This.repaint();
				}
			}
		}).start();
    }

    // Forcefully visible when the component owns the focus or the selection is being shown
    /**{@inheritDoc}*/ @Override
    public void setVisible(boolean isVisible) {
		if(!isVisible && this.isSelectionVisible() && this.getComponent().isFocusOwner()) return;
		super.setVisible(isVisible);
	}
    // The visibility of the caret depends on whether or not the selection is visible
    /**{@inheritDoc}*/ @Override
    public boolean isVisible() {
		return this.isSelectionVisible() && this.blindOff;
	}

}

The class NonEditableTextComponentCaret is very easy to use. Here is how:

    JTextComponent TC = new JTextPane();
    TC.setEditable(false);
    TC.setCaret(new NonEditableTextComponentCaret());

Done! How easy.
Enjoy coding.