在Java小程序中绘制多边形

多边形是一个封闭图形，具有将一个顶点连接到另一个顶点的有限线段集。多边形由一组 (x, y) 坐标对组成，其中每一对都是多边形的顶点。多边形的边是在两个连续坐标对之间绘制的线，并且从第一对到最后一对绘制一条线段。

我们可以通过三种方式在Java小程序中绘制多边形：

1. drawPolygon(int[] x, int[] y, int numberofpoints) ：使用给定的 x 和 y 点集绘制多边形。

   // Java program to draw polygon using
   // drawPolygon(int[] x, int[] y, int numberofpoints)
   // function
   import java.awt.*;
   import javax.swing.*;
     
   public class poly extends JApplet {
     
       // called when applet is started
       public void init()
       {
           // set the size of applet to 300, 300
           setSize(200, 200);
           show();
       }
     
       // invoked when applet is started
       public void start()
       {
       }
     
       // invoked when applet is closed
       public void stop()
       {
       }
     
       public void paint(Graphics g)
       {
           // x coordinates of vertices
           int x[] = { 10, 30, 40, 50, 110, 140 };
     
           // y coordinates of vertices
           int y[] = { 140, 110, 50, 40, 30, 10 };
     
           // number of vertices
           int numberofpoints = 6;
     
           // set the color of line drawn to blue
           g.setColor(Color.blue);
     
           // draw the polygon using drawPolygon function
           g.drawPolygon(x, y, numberofpoints);
       }
   }
   

   输出 ：
   

2. drawPolygon(Polygon p) ：使用 Polygon 类的给定对象绘制多边形。

   // Java program to draw polygon
   // using drawPolygon(Polygon p)
   // function
   import java.awt.*;
   import javax.swing.*;
     
   public class poly extends JApplet {
     
       // called when applet is started
       public void init()
       {
           // set the size of applet to 300, 300
           setSize(200, 200);
           show();
       }
     
       // invoked when applet is started
       public void start()
       {
       }
     
       // invoked when applet is closed
       public void stop()
       {
       }
     
       public void paint(Graphics g)
       {
           // x coordinates of vertices
           int x[] = { 10, 30, 40, 50, 110, 140 };
     
           // y coordinates of vertices
           int y[] = { 140, 110, 50, 40, 30, 10 };
     
           // number of vertices
           int numberofpoints = 6;
     
           // create a polygon with given x, y coordinates
           Polygon p = new Polygon(x, y, numberofpoints);
     
           // set the color of line drawn to blue
           g.setColor(Color.blue);
     
           // draw the polygon using drawPolygon
           // function using object of polygon class
           g.drawPolygon(p);
       }
   }
   

   输出 ：
   

3. drawLine(int x, int y, int x1, int y1) ：在这种方法中，我们将使用线段连接相邻顶点，并连接第一个和最后一个顶点。

   // Java code to draw a polygon
   // using  drawLine(int x, int y, int x1, int y1)
   // function
   import java.awt.*;
   import javax.swing.*;
     
   public class poly extends JApplet {
     
       // called when applet is started
       public void init()
       {
           // set the size of applet to 300, 300
           setSize(200, 200);
           show();
       }
     
       // invoked when applet is started
       public void start()
       {
       }
     
       // invoked when applet is closed
       public void stop()
       {
       }
     
       public void paint(Graphics g)
       {
           // x coordinates of vertices
           int x[] = { 10, 30, 40, 50, 110, 140 };
     
           // y coordinates of vertices
           int y[] = { 140, 110, 50, 40, 30, 10 };
     
           // number of vertices
           int numberofpoints = 6;
     
           // set the color of line drawn to blue
           g.setColor(Color.blue);
     
           // join the adjacent vertices
           for (int i = 0; i < numberofpoints - 1; i++)
               g.drawLine(x[i], y[i], x[i + 1], y[i + 1]);
     
           // join the first and last vertex
           g.drawLine(x[0], y[0], x[numberofpoints - 1], y[numberofpoints - 1]);
       }
   }
   

   输出 ：
   

注意：上述函数是Java.awt 包的一部分，属于Java.awt.Graphics 类。此外，这些代码可能无法在在线编译器中运行，请使用离线编译器。程序员可以根据需要更改 x 和 y 坐标