java - 用随机颜色绘制形状

Question

我创建了一个程序，使用 MousePressed Listiner 绘制 4 个形状。该程序应该用随机颜色绘制形状。我的程序正确绘制形状，但没有用随机颜色绘制它们。你能给我一些如何编程的想法吗？

谢谢

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.JToolBar;
import javax.swing.border.EmptyBorder;

public class Pole extends JFrame {

    public static int i;
    public static void main(String[] args) {


    JFrame frame= new JFrame("Shape Stamper!");

   JPanel container;
     JButton circle = new JButton("Circle");
     JButton square = new JButton("Square");
      JButton rectangle = new JButton("Rectangle");
      JButton oval = new JButton("Oval");


        container = new JPanel(new GridLayout(1, 4));
        container.add(circle);
        container.add(square);
        container.add(rectangle);
        container.add(oval);


     circle.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                i = 1;
            }
        });

     square.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                i = 2;
            }
        });

     rectangle.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                i = 3;
            }
        });

     oval.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) { 
                i = 4;
            }
        });


     MyComponent shape = new MyComponent();
      frame.setSize(500, 500);

      frame.add(shape, BorderLayout.CENTER);
        frame.add(container, BorderLayout.SOUTH);

        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}
}




import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.Random;

import javax.swing.JComponent;

/**
 *
 * @author Taras
 */
public class MyComponent extends JComponent {
    int i;
    Color randColor;
    public MyComponent() 
    {
        this.i = i;
        addMouseListener(new MouseHandler());
    }

    private ArrayList<Rectangle2D> arrOfRect=new ArrayList<>();
    private ArrayList<Ellipse2D> arrOfEllipse=new ArrayList<>();
   // private ArrayList<Color> randColor = new ArrayList<>();
    public void paintComponent(Graphics g)
    {

        Graphics2D g2=(Graphics2D) g;

        g.setColor(new Color(randRed(), randGreen(), randBlue()));

        for(Rectangle2D r: arrOfRect){

            //g2.setColor(Color.GREEN);

            g2.draw(r);

        }
        for(Ellipse2D e: arrOfEllipse){

            g2.draw(e);}
      repaint();


    }
    public void add(Point2D p)
    {
        double x=p.getX();
        double y=p.getY();
        if (Pole.i == 1){
                Ellipse2D ellipse = new Ellipse2D.Double(x, y, 100,100);
                //randColor = new Color(randRed(), randGreen(), randBlue());

                arrOfEllipse.add(ellipse);
            }
        if (Pole.i == 2){
        Rectangle2D rectangls=new Rectangle2D.Double(x, y, 100, 100);
        arrOfRect.add(rectangls);

        }
        if (Pole.i == 3){
        Rectangle2D rectangls=new Rectangle2D.Double(x, y, 150, 100);
        arrOfRect.add(rectangls);

        }
        if (Pole.i == 4){
                Ellipse2D ellipse = new Ellipse2D.Double(x, y, 100,50);
                arrOfEllipse.add(ellipse);
            }
    }
    private class MouseHandler extends MouseAdapter {
        public void mousePressed(MouseEvent event)
        {
            add(event.getPoint());
            //Color rColor = new Color(randRed(), randGreen(), randBlue());
            //randColor.add(rColor);
            randColor = new Color(randRed(), randGreen(), randBlue());

        }

    }

    private int randRed() {
        int red;
        Random randomNumber = new Random();
        red = randomNumber.nextInt(255);
        return red;
    }

    private int randGreen() {
        int green;
        Random randomNumber = new Random();
        green = randomNumber.nextInt(255);
        return green;
    }

    private int randBlue() {
        int blue;
        Random randomNumber = new Random();
        blue = randomNumber.nextInt(255);
        return blue;
    }
}

Answer 1

接下来您的问题是为此处的所有组件仅设置一次Color:

g.setColor(new Color(randRed(), randGreen(), randBlue()));

但是如果您想更改每个形状的颜色，则需要每次调用 setColor()。

您可以使用 Random 的一个实例更改您的 paintComponent() 方法，如下所示，您的形状将具有不同的颜色:

Random rand = new Random();
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;

    for (Rectangle2D r : arrOfRect) {
        g.setColor(new Color(rand.nextFloat(), rand.nextFloat(), rand.nextFloat()));
        g2.draw(r);

    }
    for (Ellipse2D e : arrOfEllipse) {
        g.setColor(new Color(rand.nextFloat(), rand.nextFloat(), rand.nextFloat()));
        g2.draw(e);
    }

}

在 paintComponent() 方法中调用 repaint() 也是错误的，请删除该行并在添加新形状后重新绘制面板，例如:

private class MouseHandler extends MouseAdapter {
    public void mousePressed(MouseEvent event) {
        add(event.getPoint());
        repaint();
    }
}