java - 无法将按钮置于右中位置

Question

我正在尝试弄清楚如何将按钮放置在右中位置。我添加了到目前为止我所做的事情，并且我将添加一张我想要的图。

我试图了解如何在 Swing 中确定我想要的位置，但无法真正理解每种布局的优点。

到目前为止我的代码:

package Game;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JToolBar;
import javax.swing.Timer;


public class MainWindow extends JFrame implements ActionListener {

    private JButton exit;
    private JButton start_Game;
    private ImageIcon puzzleBackground;
//  private JLabel back_Label;
//  private GridBagConstraints grid = new GridBagConstraints();
    private JPanel menu;

    public MainWindow() 
    {
        super("Welcome");
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        setSize(450,300);
        setLocationRelativeTo(null);
        this.setLayout(new FlowLayout(FlowLayout.RIGHT));
        menu = new JPanel();
        menu.setLayout(new BorderLayout());
        //setResizable(false);

        //===== Background =====
        puzzleBackground = new ImageIcon("MyBackground.jpg");
        setContentPane(new JLabel(puzzleBackground));

        exit = new JButton("Exit");
        menu.add(exit, BorderLayout.CENTER);
        exit.addActionListener(this);

        start_Game = new JButton("Start to play");
        menu.add(start_Game, BorderLayout.SOUTH);
        exit.addActionListener(this);
        start_Game.addActionListener(this);

//      
//      back_Label = new JLabel(puzzleBackground);
//      back_Label.setLayout(new BorderLayout());

        //===== Buttons =====
//      back_Label.add(exit,BorderLayout.CENTER);
//      
//      back_Label.add(start_Game,BorderLayout.EAST);
//      
        add(menu);
        setVisible(true);
    }


    public static void main(String args[])
    {
        MainWindow a = new MainWindow();
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        if(e.getSource() == exit)
        {
            System.exit(0);
        }
        else
        {
            //open start up window.
        }

    }

}

Answer 1

添加 BG 图像的更好方法是使用自定义绘制的 JPanel。然后设置面板的布局并向其中添加其他面板或组件。请注意，此处的按钮并未在很大程度上出现，因为它们被添加到JLabel中。

这里有一个替代方案，其工作原理相同，红色面板是自定义绘制背景图像的面板，而 menu 面板设置为透明(查找 opaque 方法)。

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

public class MainWindow extends JFrame {

    private JPanel menu;
    private JPanel contentPane = new JPanel(new BorderLayout(4,4));

    public MainWindow() {
        super("Welcome");
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        //setSize(450, 300); // use pack() instead
        setContentPane(contentPane);
        contentPane.setBorder(new EmptyBorder(8,8,8,8));
        contentPane.setBackground(Color.RED);
        contentPane.add(new JLabel(new ImageIcon(
                new BufferedImage(400,200,BufferedImage.TYPE_INT_RGB))));

        menu = new JPanel(new GridLayout(0,1,10,10));

        menu.add(new JButton("Exit"), BorderLayout.CENTER);
        menu.add(new JButton("Start to play"), BorderLayout.SOUTH);

        JPanel menuCenterPanel = new JPanel(new GridBagLayout());
        menuCenterPanel.add(menu);
        add(menuCenterPanel, BorderLayout.LINE_END);

        pack();
        setLocationRelativeTo(null); // do AFTER pack()
        setMinimumSize(getSize());
        setVisible(true);
    }

    public static void main(String args[]) {
        MainWindow a = new MainWindow();
    }
}