Question

我制作了一个绘制Polygon的程序，但Polygon没有显示出来。我正在尝试修复我的代码。

public static class Polygon extends JPanel {

    public Polygon() {
        setBackground(Color.black);
    }

    public void paintComponent(Graphics p)
    {
        super.paintComponent(p);
        int[] list1 = {100,50,150,200};  
        int[] list2 = {50,100,200,150};
        int n = 3;

        drawAPolygon(list1,list2,n);
    }

    public void drawAPolygon(int[] xPoints, int[] yPoints, int numPoints){
        Graphics p = getGraphics();
        p.setColor(Color.yellow);
        p.drawPolygon(xPoints, yPoints, numPoints);
    }       
}

Answer 1

getGraphics()方法不适合您。但您可以将Graphics作为参数传递。

 public static class Polygon extends JPanel {

            public Polygon() {
                setBackground(Color.black);
            }

            public void paintComponent(Graphics p)
            {
                super.paintComponent(p);
                int[] list1 = {100,50,150,200};  
                int[] list2 = {50,100,200,150};
                int n = 3;
                drawAPolygon(p,list1,list2,n);
            }

            public void drawAPolygon(Graphics p, int[] xPoints, int[] yPoints, int numPoints){
                p.setColor(Color.yellow);
                p.drawPolygon(xPoints, yPoints, numPoints);
            }       
        }

Answer 2

我不确定为什么你有一个静态类，先改变它，然后尝试下面的建议。

我会在paintComponent方法中做所有事情。这段代码对我很好：

import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;

public class Polygon extends JPanel {

    public void paintComponent(Graphics p)
    {
        super.paintComponent(p);

        int[] list1 = {100,50,150,200};  
        int[] list2 = {50,100,200,150};
        int n = 3;

        p.setColor(Color.yellow);
        p.drawPolygon(list1, list2, n);
    }    
}

这是一个带有main方法的跑步者类，所以你可以测试它：

import javax.swing.JFrame;

public class DrawPolygon {
    public static void main(String[] args) {
        Polygon panel = new Polygon();
        JFrame frame = new JFrame();
        frame.add(panel);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500, 500);
        frame.setVisible(true);
    }
}

那种颜色不能很好地显示，也许有一种方法可以让它变厚？

绘制多边形：无法找到错误

2 个答案: