constraint must be a string (or null)

Question

I can not find the error to save my life. The error is \"constraint must be a string (or null)\" I dont know why it is giving me this error, I have to be missing something s

Answer 1

You are giving dataPane a BorderLayout, but then trying to use GridBagConstraints when adding components to it --- not allowed, and even if allowed, just doesn't make sense.

Instead you have one of two options:

• Keep the container's layout as BorderLayout but use BorderLayout constants such as BorderLayout.EAST when adding components to this container, or
• Change the dataPane's layout manager to GridBagLayout, and then sure, go ahead and continue using GridBagConstraints when adding components.

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Edit
You state in comment:

so I use dataPane = new JPanel(new GridBagLayout()); then add it by add(dataPane);

Yes, it is fine to use a GridBagLayout, but I'm not sure what you mean by your second point, the one re add(dataPane) as that appears unrelated to your original problem.