Why Does Only the Top Panel Appear in My JFrame?

Only the Top Panel Appearing in JFrame

In a JFrame, the BorderLayout is the default content pane. When adding components without specifying constraints, they are placed in the center section of the BorderLayout. However, only one component can occupy this area.

To resolve this issue, use BorderLayout constraints to specify the location of each panel:

<code class="java">f.add(top, BorderLayout.PAGE_START);
f.add(mid);
f.add(bot, BorderLayout.PAGE_END);</code>

Additional Optimizations:

• Remove f.setSize(500, 500); and use pack() instead, as it sets the frame size based on its contents.
• Change f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); to f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); to properly terminate the GUI when closed.
• Remove in.setVisible(true); as components become visible when added to a visible container.
• Update the class declaration to public class EncDecExample instead of public class EncDecExample extends JFrame to avoid keeping an unnecessary reference to a frame.

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