Question

我正在尝试做一些事情，用户得到一个提示，他们可以从JColorChooser中选择一种颜色，一旦他们这样做，一个矩形弹出同一个JFrame，它的颜色与用户选择

到目前为止

代码：

import javax.swing.*;

import java.util.*;
import java.awt.*;

public class TestProjectDialog {

    static String name;


    public String getName(){
        return name;
    }

    TestProjectJPanel jpp = new TestProjectJPanel();

    public static void main(String[] args){




    JOptionPane.showMessageDialog(null, "Just about to draw a REALLY GOOD 2D car \n just need input please.");

     name= JOptionPane.showInputDialog("Imagine a car, what is it's name?");
    if(name == null || (name != null && ("".equals(name))))   
    {
        JOptionPane.showMessageDialog(null, "Invalid input/pressed cancel, closing program.");
      System.exit(0);
    }
    JOptionPane.showMessageDialog(null, "Ah okay, so it's name is " + name); 

    JFrame f = new JFrame(name);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    TestProjectJPanel jpp = new TestProjectJPanel();


    jpp.setBackground(Color.WHITE);
    f.setSize(1440,900);
    f.add(jpp.panel, BorderLayout.CENTER);
    f.add(jpp.b, BorderLayout.SOUTH);
    f.setVisible(true);



    }


}

对于具有按钮，监听器以及我希望Rectangle出现的位置的类

    import java.awt.*;
import java.awt.event.*;

import javax.swing.*;


public class TestProjectJPanel extends JFrame {



    public JButton b;
    public Color color = (Color.WHITE);
    public JPanel panel;
    public Color bodyColour;
    public Color doorColour;
    public Color wheelColour;




        public void paintComponent(Graphics g){ // Surely this shouldn't be void as it's returning a Rectangle?
            super.paintComponents(g);
            Rectangle r = new Rectangle(430,50,250,400);
            g.fillRect((int)r.getX(),(int)r.getY(),(int)r.getHeight(),(int)r.getWidth());
            g.setColor(bodyColour);
        }


    public TestProjectJPanel(){
        panel = new JPanel();
        panel.setBackground(color);

        // bodyColour button
        b = new JButton("Choose a colour for the body of the car");
        b.addActionListener(
                new ActionListener(){
                    public void actionPerformed(ActionEvent event){
                        bodyColour = JColorChooser.showDialog(null, "Pick the colour", bodyColour);
                        if(bodyColour==null) 
                            bodyColour = (Color.BLACK);

                        // TRYING TO DRAW THE RECTANGLE HERE ONCE THE USER PICKED THEIR COLOUR.

                    }
                }
                );

    }

        }

Answer 1

见Performing Custom Painting。

作为提示，请勿覆盖paint等顶级容器JFrame，创建自定义JPanel并覆盖其paintComponent方法并在那里进行自定义绘画（不要忘记致电super.paintComponent）。

提供允许您更改矩形颜色的方法，并调用repaint以请求更新面板。

如何在JButton Action Listener中绘制一个矩形

1 个答案: