Day42---学习Java第三弹

2021-08-25

例题

求矩形、圆、三角形面积系统

import java.util.Scanner;
 
public class Work1 {
    //求矩形面积
    public double rectangleArea(){
        Scanner input = new Scanner(System.in);
        System.out.println("请输入矩形的宽：");
        int width = input.nextInt();
        System.out.println("请输入矩形的高：");
        int high = input.nextInt();
        input.close();
        return width*high;
    }
    //求圆的面积
    public double circularArea(){
        Scanner input = new Scanner(System.in);
        System.out.println("请输入圆的半径：");
        int radis = input.nextInt();
        input.close();
        return 3.14*radis*radis;
    }
        
    //求三角形的面积
    public double triangleArea(){
        Scanner input = new Scanner(System.in);
        System.out.println("请输入三角形的底：");
        int sideLength1 = input.nextInt();
        System.out.println("请输入三角形的高：");
        int sideLength2 = input.nextInt();
        input.close();
        return 0.5*sideLength1*sideLength2;
    }
    public static void main(String[] args) {
        Work1 work = new Work1();
        double area = 0;
        String shape = "";
        System.out.println("1、矩形     2、三角形      3、圆");
        System.out.println("请选择图形：");
        Scanner input = new Scanner(System.in);
        int in = input.nextInt();
        switch(in) {
        case 1:
            shape = "矩形";
            area = work.rectangleArea();
            break;
        case 2:
            shape = "三角形";
            area = work.triangleArea();
            break;
        case 3:
            shape = "圆";
            area = work.circularArea();
            break;
        default:
            break;
        }
        input.close();
        System.out.println("该"+shape+"的面积为："+area);
    }
}

简易计算器（只需要考虑加减乘除）

import java.util.Scanner;
//简易计算器
public class Work2 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        double result = 0;
        System.out.println("请输入算式（逐个输入）");
        int operand1 = input.nextInt();
        String operator = input.next();
        int operand2 = input.nextInt();
        input.close();
        switch (operator) {
        case "+":
            result = operand1 + operand2;
            break;
        case "-":
            result = operand1 - operand2;
            break;
        case "*":
            result = operand1 * operand2;
            break;
        case "/":
            result = operand1 / operand2;
            break;
        default:
            break;
        }
        System.out.println("result="+result);
    }
}