JPanel 底部奇怪的白色边框

Question

我的屏幕底部有一个奇怪的白色边框。它在左下角，也就是TimeView.java

这是我的 ContentPane.java

package views;

import java.awt.BorderLayout;

import javax.swing.BoxLayout;
import javax.swing.JPanel;

public class ContentPane extends JPanel {

private static final long serialVersionUID = 1L;

private GameView gameView;
private PlayView playView;
private TimeView timeView;

public ContentPane() {      
    this.setLayout(new BorderLayout());
}

public void setGameView(GameView gameView, PlayView playView, TimeView timeView) {
    this.gameView = gameView;
    this.playView = playView;
    this.timeView = timeView;

    JPanel subPanel = new JPanel();
    subPanel.setLayout(new BoxLayout(subPanel, BoxLayout.Y_AXIS));
    subPanel.add(gameView);
    subPanel.add(timeView);

    this.add(playView, BorderLayout.CENTER);
    this.add(subPanel, BorderLayout.WEST);
}

}

这是 GameView.java

package views;

import java.awt.Color;
import java.awt.Dimension;

import javax.swing.BorderFactory;
import javax.swing.JPanel;

public class GameView extends JPanel {

private static final long serialVersionUID = 1L;

public GameView() {
    this.setBackground(Color.decode("#2A2828"));
    this.setBorder(BorderFactory.createMatteBorder(0, 0, 5, 0, Color.GRAY));
    this.setPreferredSize(new Dimension(200, 300));
}

}

这是 TimeView.java

package views;

import java.awt.Color;
import java.awt.Dimension;

import javax.swing.BorderFactory;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

public class TimeView extends JPanel {

private static final long serialVersionUID = 1L;

public TimeView() {
    this.setBackground(Color.decode("#2A2828"));
    this.setPreferredSize(new Dimension(200, 500));
}
}

这是 PlayView.java

package views;

import java.awt.Color;
import java.awt.Dimension;

import javax.swing.JPanel;

public class PlayView extends JPanel {

private static final long serialVersionUID = 1L;

public PlayView() {
    this.setBackground(Color.decode("#1F1F40"));
    this.setPreferredSize(new Dimension(1100, 800));
}

}

我已经尝试在 TimeView 上放置一个空边框，但仍然会出现奇怪的白色边框。

如果有人可以向我解释导致此问题的原因，那就太好了。

编辑：

这是 MainFrame.java

package views;

import javax.swing.JFrame;

public class MainFrame extends JFrame {

private static final long serialVersionUID = 1L;

public void setupGui(ContentPane contentPane) {
    this.setTitle("TagMan By Jesse");
    this.setContentPane(contentPane);
    this.setSize(1300, 800);
    this.setVisible(true);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setLocationRelativeTo(null);
    this.setResizable(false);
}

}

Answer 1

在许多操作系统中，使窗口不可调整大小会改变框架装饰，从而影响可用的内容空间。不过，这往往不会使容器无效，这可能会导致少量额外空间未被使用。

在设置大小或使窗口可见之前，您应该调用setResizable。

另外，因为“可用”空间是“窗口大小”减去“框架装饰”，所以您不应该依赖setSize，相反，您应该允许窗口和布局管理器 API 做出此决定为您服务，只需调用pack，它将围绕内容首选大小打包窗口，例如...

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        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 ContentPane());
                frame.setResizable(false);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class ContentPane extends JPanel {

        private static final long serialVersionUID = 1L;

        private GameView gameView;
        private PlayView playView;
        private TimeView timeView;

        public ContentPane() {
            this.setLayout(new BorderLayout());
            setGameView(new GameView(), new PlayView(), new TimeView());
        }

        public void setGameView(GameView gameView, PlayView playView, TimeView timeView) {
            this.gameView = gameView;
            this.playView = playView;
            this.timeView = timeView;

            JPanel subPanel = new JPanel();
            subPanel.setLayout(new BoxLayout(subPanel, BoxLayout.Y_AXIS));
            subPanel.add(gameView);
            subPanel.add(timeView);

            this.add(playView, BorderLayout.CENTER);
            this.add(subPanel, BorderLayout.WEST);
        }

    }

    public class GameView extends JPanel {

        private static final long serialVersionUID = 1L;

        public GameView() {
            this.setBackground(Color.decode("#2A2828"));
            this.setBorder(BorderFactory.createMatteBorder(0, 0, 5, 0, Color.GRAY));
            this.setPreferredSize(new Dimension(200, 300));
        }

    }

    public class TimeView extends JPanel {

        private static final long serialVersionUID = 1L;

        public TimeView() {
            this.setBackground(Color.decode("#2A2828"));
            this.setPreferredSize(new Dimension(200, 500));
        }
    }

    public class PlayView extends JPanel {

        private static final long serialVersionUID = 1L;

        public PlayView() {
            this.setBackground(Color.decode("#1F1F40"));
            this.setPreferredSize(new Dimension(1100, 800));
        }

    }
}

我也不鼓励使用setPreferredSize 来支持覆盖getPreferredSize，因为setPreferredSize 没有提供合适的方法来“管理”可能发生的任何更改