Question

I have a GUI im building to illustrate a tree. The JPanel that I extended isnt showing the JLabel that I created when I constructed the JPanel. Here is my JPanel code:

class NodePanel extends JPanel {
    private JLabel content;

    NodePanel() {
        this.setLayout(new FlowLayout());
        this.setBorder(new LineBorder(Color.black));
    }

    NodePanel(String str) {
        this.setLayout(new FlowLayout());
        this.setBorder(new LineBorder(Color.black));

        content = new JLabel(str);
        this.add(content);
    }
}

and here is the code where im testing it:

NodePanel n1 = new NodePanel(Integer.toString(root.getWeight()));

HuffmanGUI.tp.add(n1);
n1.setBounds((tpWidth / 2) - (panelDim / 2), vertSpace, panelDim, panelDim);

This code is in a method called by an action listener, I know it works because the panel shows up where its supposed to, but the Jlabel isnt displayed inside it. Why could this be?

Answer 1

Its hard to tell because we don’t know the context of how the code is used. It looks like you are mixing null layouts with layout managers.

I might guess that you are adding the panel to a visible GUI and you haven’t used revalidate() on the panel so the label doesn’t have a size.

If you need more help then post your SSCCE that demonstrates the problem.