java学习49天2020/8/23

1 import java.util.Scanner;
 2 //点类
 3 class Point{
 4     private float x; //横坐标
 5     private float y; //纵坐标
 6     public Point(){
 7     }
 8     public Point(float x,float y) {
 9         this.x=x;
10         this.y=y;
11     }
12     public float getX() {
13         return x;
14     }
15     public float getY() {
16         return y;
17     }
18 }
19 //矩形类
20 public class Rectangle {
21     private Point p1=new Point(); //矩形左下角点
22     private Point p2=new Point(); //矩形右上角点
23     public Rectangle() {
24     }
25     public Rectangle(Point p1, Point p2) {
26         this.p1 = p1;
27         this.p2 = p2;
28     }
29     //计算矩形面积
30     public void Area() {
31         double s;
32         s=(double)Math.abs((p2.getX()-p1.getX())*(p2.getY()-p1.getY()));
33         System.out.println(s);
34     }
35     public static void main(String[] args) {
36         Scanner in=new Scanner(System.in);
37         float a,b,c,d;
38         System.out.print("请输入矩形左下角点的坐标：");
39         a=in.nextFloat();
40         b=in.nextFloat();
41         System.out.print("请输入矩形右上角点的坐标：");
42         c=in.nextFloat();
43         d=in.nextFloat();
44         Point p1=new Point(a,b);
45         Point p2=new Point(c,d);
46         Rectangle r=new Rectangle(p1,p2);
47         System.out.print("此矩形面积：");
48         r.Area();
49     }
50 }

 

import java.util.Scanner;
 2 //日期类
 3 class Date{
 4     private int year;
 5     private int month;
 6     private int day;
 7     public Date() {
 8     }
 9     public Date(int year,int month,int day) {
10         this.year=year;
11         this.month=month;
12         this.day=day;
13     }
14     public void set() {
15         Scanner in=new Scanner(System.in);
16         year=in.nextInt();
17         month=in.nextInt();
18         day=in.nextInt();
19     }
20     public void display() {
21         System.out.println(year+"."+month+"."+day);
22     }
23 }
24 //人员类
25 public class People {
26     private int num; //编号
27     private String sex; //性别
28     private Date date=new Date(); //出生日期
29     private String ID; //身份证号
30     public People() {
31     }
32     public People(int num, String sex, Date date, String iD) {
33         super();
34         this.num = num;
35         this.sex = sex;
36         this.date = date;
37         ID = iD;
38     }
39     public void input() {
40         Scanner in=new Scanner(System.in);
41         System.out.println("请输入人员信息：");
42         System.out.print("编号：");
43         num=in.nextInt();
44         System.out.print("性别：");
45         sex=in.next();
46         System.out.print("出生日期：");
47         date.set();
48         System.out.print("身份证号：");
49         ID=in.next();
50     }
51     public void output() {
52         System.out.println("编号："+num);
53         System.out.println("性别："+sex);
54         System.out.println("出生日期：");
55         date.display();
56         System.out.println("身份证号："+ID);
57     }
58     public static void main(String[] args) {
59         People p=new People();
60         p.input();
61         p.output();
62     }
63 }

 

 二

三.例题