Question

对于我的游戏，我需要从我的面板中删除对象。我想将Square Objects存储在ArrayList中，如果用迭代器点击鼠标，则删除它们但这三个方块并没有涂在面板上。谁有人知道为什么他们不被画？

最诚挚的问候。

 public class Test {

 JFrame f = new JFrame();       
 JPanel panel =new JPanel();
 ArrayList<Square> list = new ArrayList<Square>();

public Test() {
    f.setSize(300,300); 
    f.addMouseListener(new Mouseklick());                      
    panel.setBackground(Color.YELLOW); 
    f.add(p);     
                     // adding square to list and panel
    Square a = new Square(20, 20); list.add(a); panel.add(a) ;         
    Square b = new Square(40, 40); list.add(a); panel.add(b);
    Square c = new Square(60, 60); list.add(a); panel.add(c);

    panel.repaint();
    f.setVisible(true);     
}   

 class Square extends JLabel {          

public Square(int x , int y) { // Coordinates
    setBounds(x, y, 20,20);         
    }

    @Override
    public void paint(Graphics g) {
        g.setColor(Color.RED);
        g.fillRect(0, 0, 20, 20);
    }       
}

class Mouseklick extends MouseAdapter {

   public void mousePressed(MouseEvent e) {                                 
        Iterator<Square> iter = list.iterator();
        while(iter.hasNext()){
            Square q = iter.next();
            if( q.getX()==20){ // remove square with x Coord=20
                iter.remove();
                panel.repaint();
            }
        }           
   }
}

  public static void main(String[] args) {      
    new Test();             
 }

}

Answer 1

您的JPanel由layout manager控制，该{{3}}正在决定您的组件的放置和尺寸，因为您没有提供适当的尺寸提示，标签的尺寸已根据他们的尺寸而定默认大小为0x0

此外，您只是将a添加到面板...

Square a = new Square(20, 20); 
list.add(a); 
panel.add(a) ;         
Square b = new Square(40, 40); 
list.add(a);
panel.add(b);
Square c = new Square(60, 60); 
list.add(a); 
panel.add(c);

由于组件只能驻留在单个容器上，因此实际上只有一个组件添加到容器中。

由于布局管理有些复杂，因此更好的解决方案是遵循完全自定义绘制的路线。

也就是说，利用可用的几何类并将它们直接绘制到JPanel本身。

以下示例使用了Rectangle类，这个类的两个不错的功能是......

它可以自己画画
您可以使用它来确定给定点是否在其范围内

这几乎就是你真正想做的事情

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private List<Rectangle> list = new ArrayList<Rectangle>();

        public TestPane() {
            list.add(new Rectangle(20, 20, 20, 20));
            list.add(new Rectangle(40, 40, 20, 20));
            list.add(new Rectangle(60, 60, 20, 20));

            addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    Iterator<Rectangle> iter = list.iterator();
                    while (iter.hasNext()) {
                        Rectangle q = iter.next();
                        if (q.contains(e.getPoint())) {
                            iter.remove();
                        }
                    }
                    repaint();
                }
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            for (Rectangle rect : list) {
                g2d.fill(rect);
            }
            g2d.dispose();
        }

    }

}

Swing删除Gameobjects

1 个答案: