java - JPanel 和 Frame 之间的默认彩色间距

Question

我编写了一个简单的程序，在打印“生日快乐!”时随机更改背景颜色。到屏幕上，但我看到了不需要的间距。我该如何解决这个问题？

生日.java

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class Birthday {

    DrawString panel = new DrawString();

    public Birthday() {
        JFrame f = new JFrame();

        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(panel);
        f.setTitle("Happy Birthday!");
        f.setLocation(10, 10);
        f.setVisible(true);
        f.setResizable(false);
        f.pack();

        Timer timer = new Timer(500, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                panel.repaint();
            }
        });
        timer.start();
    }

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Birthday();
            }
        });
    }
}

DrawString.java

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import javax.swing.JPanel;

public class DrawString extends JPanel {

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        int width = getWidth();
        int height = getHeight();

        int x = 350;
        int y = 250;
        int red   = random(0,255);
        int green = random(0,255);
        int blue  = random(0,255);
        Color black = new Color(0,0,0);

        Color newColor = new Color(red,green,blue);
        g.setColor(newColor);
        g.fillRect(0,0,1000,500);
        g.setColor(black);
        g.setFont(new Font(null,Font.BOLD,40));
        g.drawString("Happy Birthday!",x,y);
    }

    public static int random(int min, int max)
    {
        int range = max - min + 1;
        int number = (int) (range * Math.random() + min);
        return number;
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(1000, 500);
    }
}

Answer 1

这与可调整大小的框架边框和不可调整大小的框架边框之间的差异有关。

因为您在调用 setResizing 之前调用了 setVisible，所以窗口尚未对框架装饰的更改使用react...

尝试最后调用setVisible，例如......

    f.setResizable(false);
    f.pack();
    f.setVisible(true);

这对于一般 UI 创建来说通常是个好建议，在建立 UI 内容和属性后最后调用 setVisible ;)