Java基础之集合框架——使用真的的链表LinkedList<>（TryPolyLine）

 1 public class Point {
 2   // Create a point from its coordinates
 3   public Point(double xVal, double yVal) {
 4      x = xVal;
 5      y = yVal;
 6   }
 7 
 8   // Create a point from another point
 9   public Point(Point point) {
10      x = point.x;
11      y = point.y;
12   }
13 
14   // Convert a point to a string
15   @Override
16   public String toString() {
17      return x+","+y;
18   }
19 
20   // Coordinates of the point
21   protected double x;
22   protected double y;
23 }

 1 import java.util.LinkedList;
 2 
 3 public class PolyLine {
 4   // Construct a polyline from an array of points
 5   public PolyLine(Point[] points) {
 6     // Add the  points
 7     for(Point point : points) {
 8       polyline.add(point);
 9     }
10   }
11   // Construct a polyline from an array of coordinates
12   public PolyLine(double[][] coords) {
13     for(double[] xy : coords) {
14       addPoint(xy[0], xy[1]);
15     }
16   }
17 
18   // Add a Point object to the list
19   public void addPoint(Point point) {
20     polyline.add(point);                                               // Add the new point
21   }
22 
23   // Add a point to the list
24   public void addPoint(double x, double y) {
25     polyline.add(new Point(x, y));
26   }
27 
28   // String representation of a polyline
29   @Override
30   public String toString() {
31     StringBuffer str = new StringBuffer("Polyline:");
32 
33     for(Point point : polyline) {
34       str.append(" "+ point);                                          // Append the current point
35     }
36     return str.toString();
37   }
38 
39   private LinkedList<Point> polyline = new LinkedList<>();
40 }

 1 public class TryPolyLine {
 2   public static void main(String[] args) {
 3     // Create an array of coordinate pairs
 4     double[][] coords = { {1, 1}, {1, 2}, { 2, 3},
 5                           {-3, 5}, {-5, 1}, {0, 0} };
 6 
 7     // Create a polyline from the coordinates and display it
 8     PolyLine polygon = new PolyLine(coords);
 9     System.out.println(polygon);
10     // Add a point and display the polyline again
11     polygon.addPoint(10, 10);
12     System.out.println(polygon);
13 
14     // Create Point objects from the coordinate array
15     Point[] points = new Point[coords.length];
16     for(int i = 0; i < points.length; ++i)
17     points[i] = new Point(coords[i][0],coords[i][1]);
18 
19     // Use the points to create a new polyline and display it
20     PolyLine newPoly = new PolyLine(points);
21     System.out.println(newPoly);
22   }
23 }