Is this JPanel code good? Not showing the other JPanel when clicked on the button

Question

How to get that second JPanel to show when someone clicked on the button? The code is giving an error - unknown source. What am I missing?

package Com.global;

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Answer 1

In your actionPerformed() method, you call panel_1.setVisible(true).

However, You declare and instantiate panel_1 within the constructor. As soon as you complete execution of the constructor, you go out of scope and the panel_1 reference is lost (panel_1 is available for garbage collection).

So, by the time you invoke the actionPerformed() method, panel_1 doesn't exists.

Move the declaration of JPanel panel_1; to the top of your class, along with the other declarations and only then instantiate panel_1 within the constructor: panel_1 = new JPanel();