今天來寫k階科赫雪花的遞歸實現，(K值需要你手動輸入)至於科赫雪花是什麼請大家自行百度。
首先來思考這個程序怎麼寫，當count = 0 時就應該是一個三角形，這三個點是你一開始就確定的，以後的改變都依據這三個點發展的。當不是0的時候就需要計算相對於這個三角形的9個點，分別是每條邊上的兩個點，和它對應的三角形第三個頂點。
首先在JFrame中添加一個panel，我們需要在這個panel上畫圖。
大家再來看這個圖片，這張圖介紹了通過兩個點來計算其他三個點的過程。
現在開始在panel中畫圖：
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);//畫一個簡單的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); }現在開始寫遞歸函數。
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); } }然後在主面板中加入一個JTextField jta 它輸入的數據要傳入到number中。所以為其添加一個監聽器。 已有數據輸入就調用其中的setNumber()函數設置number變量。
jta.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { spl.setNumber(Integer.parseInt(jta.getText())); } });所以總體已經完成了，剩下的就是簡答的窗體設置。
下面貼一個完整的java代碼：
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);//畫一個簡單的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); } }效果圖：
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。