java - 使用 eclipse 在 Java 中编写 GUI 应用程序

Question

这就是我当前项目的注释中给出的示例。通常我会运行示例代码并使用它来查看一切是如何工作的。但是我不确定如何正确调用示例代码中的函数。

这是给我的:

import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.*; 
import java.awt.event.*;
import javax.swing.*;

public class Draw extends JPanel implements ActionListener
{
    JTextField tfInfo;
    JLabel lblColor, lblShapes;
    JCheckBox cbRed, cbBlue;
    ButtonGroup shapes;
    JRadioButton rbCircle, rbSquare;
    JButton btnSubmit; 
    public Draw() 
    {
        setLayout(new FlowLayout(FlowLayout.CENTER,5,5));
        tfInfo = new JTextField("Color & Shapes", 15);
        lblColor = new JLabel("Colors:");
        cbRed = new JCheckBox("Red");
        cbBlue = new JCheckBox("Blue");
        lblShapes = new JLabel("Shapes:");
        shapes = new ButtonGroup();
        rbCircle = new JRadioButton("Circle");
        rbSquare = new JRadioButton("Square");
        btnSubmit = new JButton("Submit"); 
        btnSubmit.addActionListener(this);
        add(tfInfo);
        add(lblColor);
        add(cbRed); 
        add(cbBlue); 
        add(lblShapes);
        add(rbCircle);
        add(rbSquare);
        add(btnSubmit);
        shapes.add(rbCircle);
        shapes.add(rbSquare); 
    }
    public static void main(String [] args)
    {
        Draw n = new Draw();
        n.setVisible(true);
    }
    public void actionPerformed(ActionEvent a)
    {
        if(a.getSource() == btnSubmit)
        { 
            if(cbRed.isSelected()&&cbBlue.isSelected())
            {
                if(rbCircle.isSelected())
                {
                    tfInfo.setText("urple Circle"); 
                }
                else if(rbSquare.isSelected())
                {
                    tfInfo.setText("Purple Square");
                } 
            }
            else if(cbRed.isSelected())
            {   
                if(rbCircle.isSelected())
                { 
                    tfInfo.setText("Red Circle");
                }
                else if(rbSquare.isSelected())
                {
                    tfInfo.setText("Red Square");
                }    
            }
            else if(cbBlue.isSelected())
            {  
                if(rbCircle.isSelected())
                {
                    tfInfo.setText("Blue Circle"); 
                } 
            }
            else if(rbSquare.isSelected())
            {
                tfInfo.setText("Blue Square");
            } 
        }
    }
    public class MApp extends JPanel implements MouseListener 
    {
        private boolean clicked; 
        private Rectangle r; 
        public MApp()
        {
            clicked = false;
            r = new Rectangle(10, 10, 50, 50); 
            addMouseListener(this);
        }
        public void paintComponent(Graphics g)
        {
            if(clicked)
            {
                g.setColor(Color.BLUE);
            }
            else
            {
                g.setColor(Color.RED);
            } 
            g.fillRect((int)r.getX(), (int)r.getY(),
            (int)r.getWidth(), (int)r.getHeight()); 
        }
        public void mouseClicked (MouseEvent e) 
        {
            Point p = new Point(e.getX(),e.getY()); 
            if(r.contains(p))
            {
                clicked = !clicked; 
            }
            repaint(); 
        }
        public void mousePressed (MouseEvent evnt) {}
        public void mouseReleased (MouseEvent evnt) {}
        public void mouseEntered (MouseEvent evnt) {}
        public void mouseExited (MouseEvent evnt) {} 
    }
}

Answer 1

我想我会把它分成以下几个部分:

1) 将 MApp 放入它自己的 java 文件中。另外，我将 mouseClicked 中的 repaint() 更改为:paintComponent(getGraphics());您的新 java 文件将如下所示:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.JPanel;

public class MApp extends JPanel implements MouseListener 
{
    private boolean clicked; 
    private Rectangle r; 
    public MApp()
    {
        clicked = false;
        r = new Rectangle(10, 10, 50, 50); 
        addMouseListener(this);
    }
    public void paintComponent(Graphics g)
    {
        if(clicked)
        {
            g.setColor(Color.BLUE);
        }
        else
        {
            g.setColor(Color.RED);
        } 
        g.fillRect((int)r.getX(), (int)r.getY(),
        (int)r.getWidth(), (int)r.getHeight()); 
    }
    public void mouseClicked (MouseEvent e) 
    {
        Point p = new Point(e.getX(),e.getY()); 
        if(r.contains(p))
        {
            clicked = !clicked; 
        }
        paintComponent(getGraphics()); 
    }
    public void mousePressed (MouseEvent evnt) {}
    public void mouseReleased (MouseEvent evnt) {}
    public void mouseEntered (MouseEvent evnt) {}
    public void mouseExited (MouseEvent evnt) {} 
}

下一步:创建一个主文件，如下所示:

import javax.swing.JFrame;

public class Tester {

    public static JFrame window = new JFrame("Graphics");

    public static void main(String[] args) {
        window.setBounds(100, 100,800, 800);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setLayout(null);

        MApp m = new MApp();
        m.setBounds(100,100,50,50);
        window.add(m);

        Draw d = new Draw();
        d.setBounds(0, 0, window.getWidth(), 80);
        window.add(d);

        window.setVisible(true);
    }

}

(不要忘记从 Draw 类中删除 MApp 类)

您将能够运行代码并查看正在发生的情况...这只是一个带有一些快捷方式的快速示例，但您会明白的