​ 设计计算器类 Calculator，计算加、减、乘、除和立方体体积，并且打包为 mypackage在 Calculator Java同一目录下新建文件 PackageDemo. Java，其中设计测试类引用计算器类的各方法显示计算结果。

Calculator.java

package mypackage;

public class Calculator {
    
    

    double add(double num1,double num2)
    {
    
    
        return num1 + num2;
    }
    double minus(double num1,double num2){
    
    
        return num1 - num2;
    }
    double multiple(double num1,double num2)
    {
    
    
        return num1 * num2;
    }
    double divide(double num1,double num2)
    {
    
    
        return num1 / num2;
    }
    double cube(double num1,double num2){
    
    
        return (double) Math.pow(num1,num2);
    }
}

PackageDemo.java

package mypackage;
import java.util.Scanner;
public class PackageDemo {
    
    
    public static void main(String[] args) {
    
    
        double ans;
        Scanner scanner = new Scanner(System.in);
        double num1 = scanner.nextInt();
        double num2 = scanner.nextInt();
        Calculator c=new Calculator();
        ans=c.add(num1,num2);
        System.out.println("相加："+String.format("%.2f", ans));
        ans= c.minus(num1,num2);
        System.out.println("相减："+String.format("%.2f", ans));
        ans=c.multiple(num1,num2);
        System.out.println("相乘："+String.format("%.2f", ans));
        ans=c.divide(num1,num2);
        System.out.println("相除："+String.format("%.2f", ans));
        ans=c.cube(num1,num2);
        System.out.println("乘方："+String.format("%.2f", ans));
    }
}