类的封装练习

封装点Point类和线段Line类。点有x,y属性，线段有起点和终点。主程序中创建2个点，用这两个点创建一条线段，输出线段的长度。要求：类封装完整，结果输出正确。

Line线段类

package zy;


class Line{//线段类
    private Point p1,p2;//两个点类
    public Line(Point p1,Point p2){//构造方法,传入两个Point类，保存到当前的Line类属性中
        this.p1 = p1;
        this.p2 = p2;
    }
    public double getLength(){//计算直线中两点的长度
        return p1.distance(p2);//通过调用Point类的distance方法，返回p1点和p2点两者的长度
    }
    public String ToString(){
        return "起点" + p1 + " 终点" + p2 ;
    }
    public Point getP1() {
        return p1;
    }

    public void setP1(Point p1) {
        this.p1 = p1;
    }

    public Point getP2() {
        return p2;
    }

    public void setP2(Point p2) {
        this.p2 = p2;
    }
}

Point点类

package zy;


public class Point {
    private int x, y;// x,y为点的坐标
    //求两点之间的距离
    public double distance(Point p1) {
        return Math.sqrt((p1.x -this.x)*(p1.x -this.x)+(p1.y-this.y)*(p1.y-this.y));
    }
    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
    public int getX() {
        return x;
    }
    public void setX(int x) {
        this.x = x;
    }
    public int getY() {
        return y;
    }
    public void setY(int y) {
        this.y = y;
    }
    public Point() {
        super();
        x = y =0;
    }
    public String toString() {
        return "（" + x + "," + y + "）";
    }
}

主程序

package zy;

import java.util.Random;

public class Main{
    public static void main(String[] args) {
        Random r = new Random();//生成随机数
        //点1
        Point p1 = new Point(r.nextInt(100),r.nextInt(100));
        //点2
        Point p2 = new Point(r.nextInt(100),r.nextInt(100));
        Line line = new Line(p1,p2);
        System.out.println(line.ToString());//调用Line类型的方法输出点的数据
        System.out.printf("此线段的长度为：%.1f\n",line.getLength());//输出该线段中两顶点的距离,保留一位小数
    }
}