5.1进化

package sizeys;

import java.text.DecimalFormat;
import java.util.Scanner;

public class H {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        try {
            System.out.print("请输入第一个数：");
            double x = scanner.nextDouble();
            System.out.print("请输入第二个数：");
            double y = scanner.nextDouble();
            System.out.print("请输入运算符：");
            String s = scanner.next();
            char z = s.charAt(0);
            js.yunsuan(x, y, z);
        } catch (Exception e) {
            System.out.println("请输入正确的数据！");

        }

    }

}

package sizeys;

import java.text.DecimalFormat;

public class js {

    public static void yunsuan(double x, double y, Character z) {
        DecimalFormat r = new DecimalFormat();
        r.applyPattern("#0.00");
        if (z.equals(‘+‘)) {
            jia.yunsuan1(x, y);
            // System.out.println(x + "+" + y + "=" + r.format((x + y)));
        } else if (z.equals(‘-‘)) {
            jia.yunsuan2(x, y);
            // System.out.println(x + "-" + y + "=" + r.format((x - y)));
        } else if (z.equals(‘*‘)) {
            jia.yunsuan3(x, y);
            // System.out.println(x + "*" + y + "=" + r.format((x * y)));
        } else if (z.equals(‘/‘)) {
            if (y == 0) {
                System.out.println("被除数不能为0");
            } else {
                jia.yunsuan4(x, y);
                // System.out.println(x + "/" + y + "=" + r.format((x / y)));
            }

        } else {
            System.out.println("无法识别改运算符");
        }
    }

}

package sizeys;

import java.text.DecimalFormat;

public class jia {

    public static double yunsuan1(double x, double y) {
        DecimalFormat r = new DecimalFormat();

        r.applyPattern("#0.00");
        System.out.println(x + "+" + y + "=" + r.format((x + y)));
        return x + y;
    }

    public static double yunsuan2(double x, double y) {
        DecimalFormat r = new DecimalFormat();
        r.applyPattern("#0.00");
        System.out.println(x + "-" + y + "=" + r.format((x - y)));
        return x - y;
    }

    public static double yunsuan3(double x, double y) {
        DecimalFormat r = new DecimalFormat();
        r.applyPattern("#0.00");
        System.out.println(x + "*" + y + "=" + r.format((x * y)));
        return x * y;
    }

    public static double yunsuan4(double x, double y) {
        DecimalFormat r = new DecimalFormat();
        r.applyPattern("#0.00");
        System.out.println(x + "/" + y + "=" + r.format((x / y)));
        return x / y;
    }

}

package sizeys;

import static org.junit.Assert.*;

import org.junit.Test;

public class jiaTest {

    @SuppressWarnings("static-access")
    @Test
    public void testYunsuan1() {
        jia core1 = new jia();
        double a = core1.yunsuan1(9, -3);
        // 测一下：9和-3传入我的add方法里面，结果会不会是6？
        // assertEquals(6, a);

    }

    @Test
    public void testYunsuan2() {

        jia core2 = new jia();
        double b = core2.yunsuan2(9, 4);
    }

    @Test
    public void testYunsuan3() {

        jia core3 = new jia();
        double c = core3.yunsuan3(9, -1);
    }

    @Test
    public void testYunsuan4() {

        jia core4 = new jia();
        double d = core4.yunsuan4(9, 5);
    }
}