Question

因此，每当我运行该应用程序时，框架就在那里，但是所有颜色和矩形都没有。我要制作3个不同的菜单，每个菜单都比较难处理，所以我的框架中需要3个面板

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

public class Application extends JPanel{

    public static void main(String[] args) {

        JFrame frame = new JFrame("FrogVibes");
        JPanel container = new JPanel();
        JPanel mainPanel = new JPanel();
        JPanel upgradePanel = new JPanel();
        JPanel frogPanel = new JPanel();
        JButton button = new JButton();

        mainPanel.setSize(400,690);
        upgradePanel.setSize(400,690);
        frogPanel.setSize(400,690);
        mainPanel.setBackground(Color.BLACK);
        upgradePanel.setBackground(Color.BLACK);
        frogPanel.setBackground(Color.BLACK);

        container.setLayout(new BoxLayout(container, BoxLayout.X_AXIS));
        container.add(mainPanel);
        container.add(upgradePanel);
        container.add(frogPanel);

        new Application() {
        };

        frame.setContentPane(new Container());
        frame.setSize(1280,700);
        frame.setVisible(true);
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

    }

    public void Graphics(Graphics g) {
        super.paintComponent(g);
        g.drawRect(0,700,400,100);
        g.drawRect(0, 600,100,150);
    }
}

什么是错误的位置，缺少的语句或什么

Answer 1

您需要创建Application类的实例并将其添加到JFrame：

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

public class Application extends JPanel{

    public static void main(String[] args) {

        JFrame frame = new JFrame("FrogVibes");
        JPanel application = new Application();
        frame.add(application);
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawRect(0,700,400,100);
        g.drawRect(0, 600,100,150);
    }
}

此外，该方法必须命名为paintComponent()，而不是Graphics()。现在，Swing在绘制窗口时将调用paintComponent()。

Answer 2

您只有一个错别字，您需要像container那样将创建的frame添加到frame.setContentPane(container);，而不是添加新的容器。我只是改变颜色，以便您可以看到每个面板：

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

public class Application extends JPanel{

    public static void main(String[] args) {

        JFrame frame = new JFrame("FrogVibes");
        JPanel container = new JPanel();
        JPanel mainPanel = new JPanel();
        JPanel upgradePanel = new JPanel();
        JPanel frogPanel = new JPanel();
        JButton button = new JButton("button!");

        mainPanel.setSize(400,200);
        upgradePanel.setSize(500,690);
        frogPanel.setSize(400,690);
        mainPanel.setBackground(Color.RED);
        upgradePanel.setBackground(Color.BLACK);
        frogPanel.setBackground(Color.BLUE);
        
        upgradePanel.add(button);

        container.setLayout(new BoxLayout(container, BoxLayout.X_AXIS));
        container.add(mainPanel);
        container.add(upgradePanel);
        container.add(frogPanel);

        new Application() {
        };

        frame.setContentPane(container);
        frame.setSize(1280,700);
        frame.setVisible(true);
        
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

}

public void Graphics(Graphics g) {
    super.paintComponent(g);
    g.drawRect(0,700,400,100);
    g.drawRect(0, 600,100,150);
}
}

为什么我的JPanels没有显示颜色或形状

2 个答案: