JavaFX 类 Point2D用法及代码示例

Point2D类是JavaFX的一部分。此类定义空间中的二维点。 Point2D类通过其x，y坐标表示2D点。它继承了java.lang.Object类。

该类的构造函数：

• Point2D(double x, double y)：创建具有指定x和y坐标的point2D对象。

常用方法：

方法	说明
distance(double x1, double y1)	计算此点与点(x1，y1)之间的距离。
distance(Point2D p)	计算该点与点p之间的距离。
equals(java.lang.Object obj)	返回此对象是否等于指定的对象
getX()	返回该点的x坐标
getY()	返回该点的y坐标
hashCode()	返回该点的哈希码值。

下面的程序将说明Point2D类的用法：

1. Java程序创建点2D对象并显示其坐标并找到其距原点的距离：在此程序中，我们通过使用其x，y坐标作为参数来创建一个名为point2d_1的Point2D对象。我们将使用getX()，getY()函数获得x，y的值，然后显示它。我们还在计算点到原点的距离。

   // Java program to create a point 2D  
   // object and display its coordinates 
   // and find its distance from origin 
   import javafx.geometry.Point2D; 
     
   public class Point2D_1 { 
     
       // Main Method 
       public static void main(String args[]) 
       { 
     
           // Create a point2D object 
           Point2D point2d_1 = new Point2D(20.0f, 150.0f); 
     
           double x, y; 
     
           // get the coordinates of the point 
           x = point2d_1.getX(); 
           y = point2d_1.getY(); 
     
           // display the coordinates of the point 
           System.out.println("x coordinate = " + x  
                         + ", y coordinate = " + y); 
     
           // print its distance from origin 
           System.out.println("distance from origin = " 
                           + point2d_1.distance(0, 0)); 
       } 
   }

   输出：

   x coordinate = 20.0, y coordinate = 150.0
   distance from origin = 151.32745950421557
   

2. Java程序创建3个Point2D对象并显示其坐标和距原点的距离，并检查3个点中的哪个点相似以及两个点之间的距离：在此程序中，我们通过传递其x，y坐标作为参数来创建3个Point2D对象，它们分别名为point2d_1，point2d_2，point2d_3。我们使用getX()，getY()函数获得x，y值，然后显示它。我们还在计算点到原点的距离，并为三个点中的每一个显示它。我们还使用equals()函数显示两个点是否相等，以及使用distance()函数显示两个点之间的距离。

   // Java program to create 3 Point2D objects and display 
   // their coordinates and distance from origin and 
   // check which of the 3 points are similar and  
   // their distances between two points 
   import javafx.geometry.Point2D; 
     
   public class Point2D_2 { 
     
       // Main Method 
       public static void main(String args[]) 
       { 
     
           // Create three point2D objects 
           Point2D point2d_1 = new Point2D(120.0f, 50.0f); 
           Point2D point2d_2 = new Point2D(120.0f, 50.0f); 
           Point2D point2d_3 = new Point2D(200.0f, 120.0f); 
     
           // Display the coordinates of the 3 points 
           display(point2d_1); 
           display(point2d_2); 
           display(point2d_3); 
     
           // Check whether any point is equal to other or not 
           System.out.println("Point 1 equals Point 2 = " 
                           + point2d_1.equals(point2d_2)); 
     
           System.out.println("Point 2 equals Point 3 = " 
                           + point2d_2.equals(point2d_3)); 
     
           System.out.println("Point 3 equals Point 1 = " 
                           + point2d_3.equals(point2d_1)); 
     
           // distance between two points 
           System.out.println("Distane between point 1 and point 2 = " 
                                     + point2d_1.distance(point2d_2)); 
     
           System.out.println("Distane between point 2 and point 3 = " 
                                      + point2d_2.distance(point2d_3)); 
     
           System.out.println("Distane between point 3 and point 1 = " 
                                       + point2d_3.distance(point2d_1)); 
       } 
     
       // display method 
       public static void display(Point2D point2d) 
       { 
     
           double x, y; 
     
           // get the coordinates of the point 
           x = point2d.getX(); 
           y = point2d.getY(); 
     
           // display the coordinates of the point 
           System.out.println("x coordinate = " + x  
                         + ", y coordinate = " + y); 
     
           // print its distance from origin 
           System.out.println("Distance from origin = " 
                             + point2d.distance(0, 0)); 
       } 
   }

   输出：

   x coordinate = 120.0, y coordinate = 50.0
   Distance from origin = 130.0
   x coordinate = 120.0, y coordinate = 50.0
   Distance from origin = 130.0
   x coordinate = 200.0, y coordinate = 120.0
   Distance from origin = 233.23807579381202
   Point 1 equals Point 2 = true
   Point 2 equals Point 3 = false
   Point 3 equals Point 1 = false
   Distane between point 1 and point 2 = 0.0
   Distane between point 2 and point 3 = 106.30145812734649
   Distane between point 3 and point 1 = 106.30145812734649
   

注意：以上程序可能无法在在线IDE中运行。请使用离线编译器。

参考：https://docs.oracle.com/javafx/2/api/javafx/geometry/Point2D.html