单击按钮向JPanel添加形状 [英] Adding shapes to JPanel on a button click

问题描述

我有一个带有按钮的Class Circle和一个带有jPanel的Class我想要做的是当点击该按钮时，将在面板上绘制一个圆圈，每次我点击该按钮并更改x和y怎么没有在这里实现我在JPanel上一遍又一遍地圈了一圈。
如何做到这一点，或者有没有办法做我描述的，无论我的代码如何，但我希望类圈扩展Shape。

  public class Window {
 
 private JFrame frame; 
 private JPanel panel = new JPanel（）; 
 Circle c = new Circle（frame，panel）; 
 //其他一些按钮
。 
。 
 //一些代码设置面板网格包的constaraints和背景然后
 frame.getContentPane（）。add（panel，gbc_panel）; 
} 
  

然后圆圈类

  public class Circle extends Shape实现ActionListener {
 
 private JPanel Panel; 
 private GridBagConstraints gbc_btnCircle; 
 private JButton btnCircle; 
 
 public void setPanel（JPanel panel）{
 Panel = panel; 
} 
 
 public Circle（JFrame框架，JPanel面板）{
 btnCircle = new JButton（Circle）; 
 //设置网格包约束的一些代码然后
 frame.getContentPane（）。add（btnCircle，gbc_btnCircle）; 
 setPanel（面板）; 
 btnCircle.addActionListener（this）; 
 
} 
 
 public void paint（Graphics g）{
 super.paintComponents（g）; 
 g.setColor（Color.red）; 
 g.fillOval（100,100,100,100）; 
 Panel.add（this）; 
} 
 
 public void actionPerformed（ActionEvent arg0）{
 repaint（）; 
} 
} 
  

解决方案

你有点错误的想法。在绘图面板中，您应该有列表< Circle> 。在绘图面板的 paintComponent 方法中，您应该遍历列表以绘制每个圆圈

  class Circle {
 int x，int y，int width，int height; 
 public Circle（int x，int y，int width，int height）{
 ... set em 
} 
 public void draw（Graphics g）{
 g.fillOval（x，y，width，height）; 
} 
} 
类DrawingPanel扩展JPanel {
 List< Circle> circles = new ArrayList<>（）; 
 
 @Override 
 protected void paintComponent（Graphics g）{
 super.paintComponent（g）; 
 for（Circle circle：circles）{
 circle.draw（g）; 
} 
} 
 
 //不要忘记覆盖公共维度getPreferredSize（）
} 
  

要在列表中添加更多圈子，只需在 DrawingPanel中有一个 addCircle 方法 class

  public void addCircle（Circle circle）{
 circles.add（circle）; 
 repaint（）; 
} 
  

至于按钮，你应该在<$ c中创建它$ c> Window 类。在 ActionListener 中，只需创建一个 new Circle 并添加 DrawingPanel 通过调用 addCircle 方法

---

除此之外， Circle 不需要扩展 Shape 。 Shape API已经有一个 Ellipse2D 等级，你可以从

$ b $创建圈子p> class DrawingPanel扩展JPanel {
List< Ellipse2D> circles = new ArrayList<>（）;

@Override
protected void paintComponent（Graphics g）{
super.paintComponent（g）;
Graphics2D g2 =（Graphics2D）g.create（）;
for（Ellipse2D circle：circles）{
g2.fill（circle）;
}
g2.dispose（）;
}
//不要忘记覆盖公共维度getPreferredSize（）
}


• 请参阅 2D图形

---

更新：完整示例

  import java.awt.BorderLayout; 
 import java.awt.Dimension; 
 import java.awt.Graphics; 
 import java.awt.event.ActionEvent; 
 import java.awt.event.ActionListener; 
 import java.util.ArrayList; 
 import java.util.List; 
 import java.util.Random; 
 import javax.swing.JButton; 
 import javax.swing.JFrame; 
 import javax.swing.JPanel; 
 import javax.swing.SwingUtilities; 
 
公共类CirclesDemo {
 
 public static void main（String [] args）{
 SwingUtilities.invokeLater（new Runnable（）{
 public void run（）{
 new CirclesDemo（）; 
} 
}）; 
} 
 
 public CirclesDemo（）{
 JFrame frame = new JFrame（）; 
 frame.add（面板）; 
 frame.add（createButton（），BorderLayout.PAGE_END）; 
 frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 frame.pack（）; 
 frame.setLocationRelativeTo（null）; 
 frame.setVisible（true）; 
} 
 
 private final DrawingPanel panel = new DrawingPanel（）; 
 
 private JButton createButton（）{
 JButton button = new JButton（Add Circle）; 
 button.addActionListener（new ActionListener（）{
 public void actionPerformed（ActionEvent e）{
 int [] circleValues = generateRandomValues（300,300,50,150）; 
 int x = circleValues [0]; 
 int y = circleValues [1]; 
 int width = circleValues [2]; 
 int height = width; 
 Circle circle = new Circle（ x，y，width，height）; 
 panel.addCircle（circle）; 
} 
}）; 
返回按钮; 
} 
 
 private int [] generateRandomValues（int maxX，int maxY，
 int minSize，int maxSize）{
 Random random = new Random（）; 
 int [] values = new int [3]; 
 values [0] = random.nextInt（maxX）; 
 values [1] = random.nextInt（maxY）; 
 values [2] = Math.min（random.nextInt（maxSize）+ minSize，maxSize）; 
返回值; 
} 
 
 class Circle {
 
 int x，y，width，height; 
 
 public Circle（int x，int y，int width，int height）{
 this.x = x; 
 this.y = y; 
 this.width = width; 
 this.height = height; 
} 
 
 public void draw（Graphics g）{
 g.drawOval（x，y，width，height）; 
} 
} 
 
类DrawingPanel扩展JPanel {
 
 List< Circle> circles = new ArrayList<>（）; 
 
 @Override 
 protected void paintComponent（Graphics g）{
 super.paintComponent（g）; 
 for（Circle circle：circles）{
 circle.draw（g）; 
} 
} 
 
 public void addCircle（Circle circle）{
 circles.add（circle）; 
 repaint（）; 
} 
 
 @Override 
 public Dimension getPreferredSize（）{
 return new Dimension（400,400）; 
} 
} 
} 
  

I have a Class Circle with a button and a Class with a jPanel what i want to do is when that button is clicked a circle will be drawn on the panel and each time i click that button and change x and y "some how not implemented here" i got a circle on the JPanel over and over . How to do that, or is there a way to do what i descriped regardless of my code but i want the class circle to extends Shape.

public class Window{

  private JFrame frame;
  private JPanel panel = new JPanel();
  Circle c = new Circle(frame, panel);
  // some other buttons 
  .
  .
 // some code to set the panel grid bag constaraints and background then
 frame.getContentPane().add(panel, gbc_panel);
}

then the Circle Class

public class Circle extends Shape implements ActionListener{

  private JPanel Panel;
  private GridBagConstraints gbc_btnCircle;
  private JButton btnCircle;

  public void setPanel(JPanel panel) {
      Panel = panel;
  }

 public Circle(JFrame frame, JPanel panel){
    btnCircle = new JButton("Circle");
    // some code to set grid bag constraint then
    frame.getContentPane().add(btnCircle, gbc_btnCircle);
    setPanel(panel);        
    btnCircle.addActionListener(this);

 }

  public void paint(Graphics g) {
      super.paintComponents(g);
      g.setColor(Color.red);        
      g.fillOval(100, 100, 100, 100);     
      Panel.add(this);
  }

  public void actionPerformed(ActionEvent arg0) {
    repaint();      
  }
}

解决方案

You kinda have the wrong idea. In your drawing panel, you should have a List<Circle>. And in the paintComponent method of the drawing panel, you should iterate through the list to draw each circle

class Circle {
    int x, int y, int width, int height;
    public Circle (int x, int y, int width, int height) {
        ... set em
    }
    public void draw(Graphics g) {
        g.fillOval(x, y, width, height);
    }
}
class DrawingPanel extends JPanel {
    List<Circle> circles = new ArrayList<>();

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        for (Circle circle : circles) {
            circle.draw(g);
        }
    }

    // Dont forget to override public Dimension getPreferredSize()
}

To add more Circles to the list, just have a addCircle method in the DrawingPanel class

public void addCircle(Circle circle) {
    circles.add(circle);
    repaint();
}

As far as the button, you should be creating it in the Window class. In the ActionListener, just create a new Circle and add it the DrawingPanel by calling the addCircle method

---

An aside, Circle doesn't need the extend Shape. The Shape API already has an Ellipse2D class, which you can create circles from

class DrawingPanel extends JPanel {
    List<Ellipse2D> circles = new ArrayList<>();

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g.create();
        for (Ellipse2D circle : circles) {
            g2.fill(circle);
        }
        g2.dispose();
    }
    // Dont forget to override public Dimension getPreferredSize()
}

• See 2D Graphics

---

UPDATE: full example

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class CirclesDemo {

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

    public CirclesDemo() {
        JFrame frame = new JFrame();
        frame.add(panel);
        frame.add(createButton(), BorderLayout.PAGE_END);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    private final DrawingPanel panel = new DrawingPanel();

    private JButton createButton() {
        JButton button = new JButton("Add Circle");
        button.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e) {
                int[] circleValues = generateRandomValues(300, 300, 50, 150);
                int x = circleValues[0];
                int y = circleValues[1];
                int width = circleValues[2];
                int height = width;
                Circle circle = new Circle(x, y, width, height);
                panel.addCircle(circle);
            }
        });
        return button;
    }

    private int[] generateRandomValues(int maxX, int maxY, 
                                       int minSize, int maxSize) {
        Random random = new Random();
        int[] values = new int[3];
        values[0] = random.nextInt(maxX);
        values[1] = random.nextInt(maxY);
        values[2] = Math.min(random.nextInt(maxSize) + minSize, maxSize);
        return values;
    }

    class Circle {

        int x, y, width, height;

        public Circle(int x, int y, int width, int height) {
            this.x = x;
            this.y = y;
            this.width = width;
            this.height = height;
        }

        public void draw(Graphics g) {
            g.drawOval(x, y, width, height);
        }
    }

    class DrawingPanel extends JPanel {

        List<Circle> circles = new ArrayList<>();

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            for (Circle circle : circles) {
                circle.draw(g);
            }
        }

        public void addCircle(Circle circle) {
            circles.add(circle);
            repaint();
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(400, 400);
        }
    }
}

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