java递归实现科赫雪花

2019-11-26 09:53:48

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今天来写k阶科赫雪花的递归实现，(K值需要你手动输入)至于科赫雪花是什么请大家自行百度。

首先来思考这个程序怎么写，当 count = 0 时就应该是一个三角形，这三个点是你一开始就确定的，以后的改变都依据这三个点发展的。当不是0的时候就需要计算相对于这个三角形的9个点，分别是每条边上的两个点，和它对应的三角形第三个顶点。

首先在JFrame中添加一个panel，我们需要在这个panel上画图。

大家再来看这个图片，这张图介绍了通过两个点来计算其他三个点的过程。

现在开始在panel中画图：

static class showpanel extends JPanel{     int number = 0;     public void setNumber(int number) {       this.number = number;       repaint();     }     public void paintComponent(Graphics g) {       super.paintComponent(g);//画一个简单的panel              int side =(int)(Math.min((int)getWidth(),(int)getHeight())*0.8);       int high =(int)(side*Math.cos(Math.toRadians(30)));               Point p1 = new Point(getWidth() / 2, 10);        Point p2 = new Point(getWidth() / 2 - side / 2, 10 + high);        Point p3 = new Point(getWidth() / 2 + side / 2, 10 + high);                playKochSnowFlake(g, number, p1, p2);        playKochSnowFlake(g, number, p2, p3);        playKochSnowFlake(g, number, p3, p1);            }

现在开始写递归函数。

public static void playKochSnowFlake(Graphics g,int number,Point p1,Point p2) {       if(number == 0){         g.drawLine(p1.x, p1.y,p2.x, p2.y);       }       else{          int deltaX = p2.x - p1.x;           int deltaY = p2.y - p1.y;            Point x = new Point(p1.x + deltaX / 3, p1.y + deltaY / 3);           Point y = new Point(p1.x + deltaX * 2 / 3, p1.y + deltaY * 2 / 3);           Point z = new Point(            (int)((p1.x + p2.x) / 2 + Math.sin(Math.toRadians(60)) * (p1.y - p2.y) / 3),            (int)((p1.y + p2.y) / 2 + Math.sin(Math.toRadians(60)) * (p2.x - p1.x) / 3));           playKochSnowFlake(g, number - 1, p1, x);           playKochSnowFlake(g, number - 1, x, z);           playKochSnowFlake(g, number - 1, z, y);           playKochSnowFlake(g, number - 1, y, p2);       }     }

然后在主面板中加入一个JTextField jta 它输入的数据要传入到number中。所以为其添加一个监听器。已有数据输入就调用其中的setNumber()函数设置number变量。

jta.addActionListener(new ActionListener() {              public void actionPerformed(ActionEvent arg0) {         spl.setNumber(Integer.parseInt(jta.getText()));              }     });

所以总体已经完成了，剩下的就是简答的窗体设置。

下面贴一个完整的java代码：

import java.awt.BorderLayout; import java.awt.FlowLayout; import java.awt.Graphics; import java.awt.Point; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JTextField;  public class SnowFlake extends JFrame {      private JTextField jta = new JTextField(5);   private showpanel spl = new showpanel();      static class showpanel extends JPanel{     int number = 0;     public void setNumber(int number) {       this.number = number;       repaint();     }     public void paintComponent(Graphics g) {       super.paintComponent(g);//画一个简单的panel              int side =(int)(Math.min((int)getWidth(),(int)getHeight())*0.8);       int high =(int)(side*Math.cos(Math.toRadians(30)));               Point p1 = new Point(getWidth() / 2, 10);        Point p2 = new Point(getWidth() / 2 - side / 2, 10 + high);        Point p3 = new Point(getWidth() / 2 + side / 2, 10 + high);                playKochSnowFlake(g, number, p1, p2);        playKochSnowFlake(g, number, p2, p3);        playKochSnowFlake(g, number, p3, p1);            }     public static void playKochSnowFlake(Graphics g,int number,Point p1,Point p2) {       if(number == 0){         g.drawLine(p1.x, p1.y,p2.x, p2.y);       }       else{          int deltaX = p2.x - p1.x;           int deltaY = p2.y - p1.y;            Point x = new Point(p1.x + deltaX / 3, p1.y + deltaY / 3);           Point y = new Point(p1.x + deltaX * 2 / 3, p1.y + deltaY * 2 / 3);           Point z = new Point(            (int)((p1.x + p2.x) / 2 + Math.sin(Math.toRadians(60)) * (p1.y - p2.y) / 3),            (int)((p1.y + p2.y) / 2 + Math.sin(Math.toRadians(60)) * (p2.x - p1.x) / 3));           playKochSnowFlake(g, number - 1, p1, x);           playKochSnowFlake(g, number - 1, x, z);           playKochSnowFlake(g, number - 1, z, y);           playKochSnowFlake(g, number - 1, y, p2);       }     }   }      public SnowFlake() {     JPanel panel = new JPanel();     panel.setLayout(new FlowLayout());     panel.add(new JLabel("Please input the number"));     panel.add(jta);     add(spl,BorderLayout.CENTER);     add(panel,BorderLayout.SOUTH);     jta.addActionListener(new ActionListener() {              public void actionPerformed(ActionEvent arg0) {         spl.setNumber(Integer.parseInt(jta.getText()));              }     });   }   public static void main(String args[]) {     SnowFlake snowFlake = new SnowFlake();     snowFlake.setSize(300, 300);     snowFlake.setTitle("SnowFlake");     snowFlake.setLocationRelativeTo(null);     snowFlake.setVisible(true);   } }

效果图：