嘗試代碼一個小程序，畫一個帶有for循環的SierpinskiTriangle

Question

嗨，每一個，所以我想寫一個代碼，當我運行它會畫一個SierpinskiTriangle。該程序必須有一個for循環，我已經有，但當我試圖讓程序complile時，我有一個問題。它說雙不能轉換爲Point2D任何人都可以幫助我嗎？

import javax.swing.*; 
import java.awt.*; 
import java.awt.geom.Line2D; 

public class ST extends JFrame { 

    int N = 50000; 
    double sqrt3 = Math.sqrt(3); 
    double x = 0.0, y = 0.0; 

public static void main(String args[]) { 
    ST t = new ST(); 
    t.add(new JComponent() { 
     public void paintComponent(Graphics g) { 
      Graphics2D g2d = (Graphics2D) g; 
      g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE); 
      for (int i = 0; i < N; i++) { 
       double r = Math.random(); 
       double x0, y0; 

       if (r < 1./3.) { 
        x0 = 0.0; y0 = 0.0; 
       } else if (r < 2./3.) { 
        x0 = 0.0; y0 = 2.0 ; 
       } else { 
        x0 = sqrt3; y0 = 1.0; 
       } 
       double x = (x0 + x)/2; 
       double y = (y0 + y)/2; 

       Shape l = new Line2D.Double(x,y); 
       g2d.draw(l); 

      } 
     } 
    }); 

    t.setDefaultCloseOperation(EXIT_ON_CLOSE); 
    t.setSize(220, 300); 
    t.setVisible(true); 
} 
} 

Answer 1

截至http://docs.oracle.com/javase/7/docs/api/java/awt/geom/Line2D.Double.html Java API的講述，類Line2D.Double有兩個構造函數：

Line2D.Double(double x1, double y1, double x2, double y2) 

和

Line2D.Double(Point2D p1, Point2D p2) 

，因爲你指定的兩個參數，Java編譯器假定後者。