Center JLabel in BorderLayout with a button at line end

问题

I have a header on a section of my swing layout, and I want to have text centered horizontally across the whole width of the section, but also have a button on only the right side. It should look like this:

 /------Same width------\           /------Same width------\
[------------------------]Text here[----------------[Button]]

I am currently using a BorderLayout, with the text in the center and the button at the line end, but the text is centered not counting the button, as such:

 /----Same width----\           /---Same width----\
[--------------------]Text here[-------------------][Button]]

回答1:

I'm not sure if this is the answer you really want, but you could use a different layout manager, like GridBagLayout

import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class JavaApplication295 {

    public static void main(String[] args) {
        new JavaApplication295();
    }

    public JavaApplication295() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
//          gbc.fill = GridBagConstraints.HORIZONTAL;
            gbc.weightx = 1;

            add(new JLabel("Look ma, no hands"), gbc);

            gbc.anchor = GridBagConstraints.EAST;
            add(new JButton("No Allowance"), gbc);
        }

    }


}

Now, the problem with this, is both components are actually positioned at the same location, the difference is, the button is anchored to the right position of the cell, this means that when the layout is been calculated, they will overlap....

回答2:

Here is an approach using the OverlayLayout which was designed to have multiple components painted on the z axis:

import java.awt.*;
import javax.swing.*;

public class SSCCE extends JPanel
{
    public SSCCE()
    {
        JLabel label = new JLabel("I'm a Centered Label");
        Box labelBox= Box.createHorizontalBox();
        labelBox.add(Box.createHorizontalGlue());
        labelBox.add(label);
        labelBox.add(Box.createHorizontalGlue());

        JButton button = new JButton("Button");
        Box buttonBox= Box.createHorizontalBox();
        buttonBox.add(Box.createHorizontalGlue());
        buttonBox.add(button);

        setLayout( new OverlayLayout(this) );
        add(buttonBox);
        add(labelBox);
    }

    private static void createAndShowGUI()
    {
        JFrame frame = new JFrame("SSCCE");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new SSCCE(), BorderLayout.NORTH);
        frame.setLocationByPlatform( true );
        frame.pack();
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowGUI();
            }
        });
    }
}

As the width decreases the button will paint over the label.

来源：https://stackoverflow.com/questions/29480695/center-jlabel-in-borderlayout-with-a-button-at-line-end