Only One Component Shows Up in JFrame

This question stems from a user encountering an issue where only the top component of their GUI is visible when the program runs. The user's code attempts to display multiple panels and text fields in the frame, but only one component is initially visible. This discrepancy leads them to suspect that other elements are being obscured.

Solution

After examining the code, it becomes evident that the issue lies in the BorderLayout of the JFrame's content pane. The BorderLayout only allows one component to occupy the center position, which is where all the components were initially placed.

To resolve this, the user should assign specific constraints to each component when adding it to the BorderLayout. The following code snippet demonstrates this approach:

f.add(top, BorderLayout.PAGE_START);
f.add(mid);
f.add(bot, BorderLayout.PAGE_END);

This code positions the top panel at the start of the frame, leaving the middle and bottom panels unconstrained. As a result, they will be displayed vertically below the top panel.

Additional Improvements

Besides resolving the visibility issue, the user also expressed a desire to enhance the program's performance. Here are a few additional suggestions:

• Remove f.setSize(500, 500); and call pack() immediately before setVisible(true) to optimize the frame's size based on its contents.
• Change f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); to f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); for a more graceful exit strategy.
• Omit setVisible(true) calls for individual components, as they become visible by default upon being added to a top-level container.
• Remove the unnecessary statement public class EncDecExample extends JFrame and replace it with public class EncDecExample.

By implementing these changes, the program will not only display all components as intended but also run more efficiently and close seamlessly when the user presses the close button.

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