Change dimensions of JButton

问题

I have problem with this. The button is taking up the entire JFrame. I've tried changing the dimensions of the JFrame and the JButton but with no changed. It's completely hiding a JTable underneath. Could someone please tell me what I'm doing wrong.

JFrame FRAME = new JFrame();
  JButton BUTTON = new JButton("OK");
  FRAME.add(new JScrollPane(TableName));
  BUTTON.setPreferredSize(new Dimension(20,30));
  FRAME.add(BUTTON);
  FRAME.setSize(700, 600);
  FRAME.setVisible(true);
  FRAME.setLocationRelativeTo(null);

回答1:

The default layout manager for a a JFrame is a BorderLayout. You are attempting to add two component the CENTER which is not allowed. Only the last one added will be displayed.

You need to specify constraints when adding components to a BorderLayout. Your code should be something like:

  frame.add(new JScrollPane(TableName), BorderLayout.CENTER);
  button.setPreferredSize(new Dimension(20,30));
  frame.add(button, BorderLayout.PAGE_START);

Also, variables names should NOT be upper cased. Follow Java convention.

Read the section from the Swing tutorial on How to Use BorderLayout for more information and working examples. The tutorial code will also show you how to better structure your program so you follow Swing coding conventions.

回答2:

Don't add the button straight to the frame, create a JPanel first, add the button to the panel then add the panel to the frame.

回答3:

    JFrame frame = new JFrame();
    // frame.setBounds(x axis, y axis, weight, height)
    frame.setBounds(10,10,304,214);
    frame.getContentPane().setLayout(null);

    JButton button = new JButton("Button");
    button.setBounds(98, 75, 126, 39);
    frame.getContentPane().add(button);
    frame.setVisible(true);

来源：https://stackoverflow.com/questions/36812260/change-dimensions-of-jbutton