java 在 Java 小程序中绘制多边形

在 Java 小程序中绘制多边形

原文:https://www.geeksforgeeks.org/draw-polygon-java-applet/

多边形是一个封闭图形，其中有限的线段将一个顶点连接到另一个顶点。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的坐标对之间绘制的线，线段是从第一个坐标对到最后一个坐标对绘制的。

我们可以通过三种方式在 java 小程序中绘制多边形:

drawPolygon(int[] x, int[] y, int numberofpoints) : draws a polygon with the given set of x and y points.

```java // 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:
drawPolygon(Polygon p) : draws a polygon with the given object of Polygon class.

```java // 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:
drawLine(int x, int y, int x1, int y1) : In this method we would connect adjacent vertices with a line segment and also connect the first and last vertex.

```java // 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: