JLabel tooltiptext not showing

Question

I expected this to be very simple and straightforward, but tooltiptext is not showing upon hovering the mouse over. I tried printing the text and it prints correctly. Any comments what I'm doing wrong?

public class gui2 extends JFrame {
private JLabel item1;
public gui2() {
    super("The title bar");
    setLayout(new FlowLayout());
    item1 = new JLabel("label 1");
    item1.setToolTipText("This is a message");
    String str = item1.getToolTipText();
    System.out.println(str);
    add(item1);
}

   class gui {
public static void main(String[] args) {

    gui2 g2 = new gui2();
    g2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    g2.setSize(400, 200);
    g2.setVisible(true);
}

} }

Answer 1

As mentioned by @restricteur your code does not compile.

This is due to the fact that your class gui which holds the main(..) is nested within another class, hence no static declaration of method is allowed unless the nested class is marked static. ( I simply moved/un-nested Gui out from Gui2)

Besides that your code does work, I think you are being hasty - hold the mouse over JLabel for like 3-4 seconds and you should see the ToolTip appear:

(using your code with no compilation error of course):

Suggestions on code:

1) Please watch java naming conventions i.e class names should begin with a capital letter and each new word thereafter should also i.e gui becomes Gui or GUI but I prefer the former.

2) Dont call setSize on JFrame use and= appropriate LayoutManager and call pack() on JFrame before setting it visible (but after components have been added).

3) Dont extend JFrame unnecessarily simply create an instance and use that.

4) Always create and manipulate Swing Components on Event Dispatch Thread via SwingUtilities.invokeLater(Runnable r) block.

5) Opt for setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); unless using Timers as this will allow main(..) to continue regardless if GUI is exited.

Here is code with above fixes:

import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;

class Gui2 {

    private JLabel item1;
    private JFrame frame;

    public Gui2() {
        frame = new JFrame("The title bar");
        frame.setLayout(new FlowLayout());
        item1 = new JLabel("label 1");
        item1.setToolTipText("This is a message");
        String str = item1.getToolTipText();
        System.out.println(str);
        frame.add(item1);
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}

class Gui {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Gui2();
            }
        });
    }
}

Answer 2

Your code does not compile even if you add the imports. Here is your code corrected and working :

import java.awt.FlowLayout;

import javax.swing.JFrame;
import javax.swing.JLabel;

public class Gui {
    public static void main(String[] args) {

        Window window = new Window();
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setSize(400, 200);
        window.setVisible(true);
    }
}

class Window extends JFrame {
    private static final long serialVersionUID = 1L;
    private JLabel jlabel;

    public Window() {
        super("The title bar");
        setLayout(new FlowLayout());
        jlabel = new JLabel("label 1");
        jlabel.setToolTipText("This is a message");
        String str = jlabel.getToolTipText();
        System.out.println(str);
        add(jlabel);
    }
}