Question

求解释Java编程问题

设计名为MyPoint的类表示一个平面坐标点--具有x坐标和y坐标的点，该类包括，
成员变量：x、y；double型；
无参数的构造方法：MyPoint( )，创建坐标点0，0）；
带参数的构造方法:MyPoint(double x,double y)创建一个坐标点(x，y)；
成员方法：getX()、getY()，返回坐标点相应的值；
成员方法：distance()，返回MyPoint类型的两个点之间的距离；
编写测试程序创建两个点(0，0)和(10，30.5)，并显示它们之间的距离。

Answer 1

public class MyPoint {

private double X;
private double Y;
public double getX() {
return X;
}
public void setX(double x) {
X = x;
}
public double getY() {
return Y;
}
public void setY(double y) {
Y = y;
}
public MyPoint(double x, double y) {
super();
X = x;
Y = y;
}
public MyPoint() {
super();
}

public double distanceX(MyPoint p1,MyPoint p2){
return Math.abs((p1.getX()-p2.getX());
}

public double distanceY(MyPoint p1,MyPoint p2){
return Math.abs(p1.getY()-p2.getY());
}

public double distance(MyPoint p1,MyPoint p2){
return Math.sqrt(distanceX(p1, p2)*distanceX(p1, p2)+distanceY(p1, p2)*distanceY(p1, p2));
}

public static void main(String[] args) {
MyPoint p1=new MyPoint(0,0);
MyPoint p2=new MyPoint(10,30.5);

double result1 = new MyPoint().distanceX(p1, p2);
double result2 = new MyPoint().distanceX(p1, p2);
double result3 = new MyPoint().distanceX(p1, p2);

System.out.println(result1);
System.out.println(result2);
System.out.println(result3);
}
}

Answer 2

package com.pb.test;
public class MyPoint { private double x;
private double y;

public MyPoint(){
this.x = 0;
this.y = 0;
}

public MyPoint(double x,double y){
this.x = x;
this.y = y;
}

public double getX() {
return x;
}
public void setX(double x) {
this.x = x;
}
public double getY() {
return y;
}
public void setY(double y) {
this.y = y;
}

public double distance(MyPoint point1, MyPoint point2) {
return Math.sqrt((point1.x - point2.x) * (point1.x - point2.x)
+ (point1.y - point2.y)*(point1.y - point2.y));
}
}
看看这个，修改了distance方法，通过了测试