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一、题1

1.1 问题描述

 (1)创建一个用于数学运算接口，算数运算加、减、乘和除都继承该接口并实现具体的算数运算。(2)编写一个测试类进行运行测试。

1.2 代码块

package mypackage;
import java.util.Scanner;
public interface IComputer {
    int computer(int one,int two);

    class Add implements IComputer{
        public int computer(int one, int two) {
            return one+two;
        }
    }

    class Sub implements IComputer{
        public int computer(int one, int two) {
            return one-two;
        }
    }
    class Mul implements IComputer{
        public int computer(int one, int two) {
            return one*two;
        }
    }
    class Div implements IComputer{
        public int computer(int one, int two) {
            if(two==0){
                System.out.println("Divide by zero, meaningless");
                System.exit(0);
            }
            return one/two;       //若类型为short、int、long，除数为0会报错
        }
    }
    class UseComputer{
        public static void useCom(IComputer com,int one,int two){
            System.out.println(com.computer(one,two));
        }
    }
}

package mypackage;

import java.util.Scanner;

public class Test {
    public static void main(String args[]) {
        Scanner sc=new Scanner(System.in);
        int a=sc.nextInt();
        int b=sc.nextInt();
        IComputer.UseComputer.useCom(new IComputer.Add(),a,b);
        IComputer.UseComputer.useCom(new IComputer.Sub(),a,b);
        IComputer.UseComputer.useCom(new IComputer.Mul(),a,b);
        IComputer.UseComputer.useCom(new IComputer.Div(),a,b);
    }
}

1.3 运行截图

二、题2

2.1 问题描述

 (1)定义一个水果抽象类，该类中提供一个水果种植抽象方法，苹果、草莓都继承水果抽象类，并实现该抽象方法。(2)编写测试类进行运行测试。

2.2 代码块

package CumtJava;

abstract class Fruit
{
    abstract double getweight();
}
class Apple extends Fruit //苹果
{
    double w;
    String s;
    Apple(double w,String s)
    {
        this.w=w;
        this.s=s;
    }
    public double getweight()
    {
        return w;
    }
}
class Peach extends Fruit //桃子
{
    double w;
    String s;
    Peach(double w,String s)
    {
        this.w=w;
        this.s=s;
    }
    public double getweight()
    {
        return w;
    }
}
class Orange extends Fruit //橘子
{
    double w;
    String s;
    Orange(double w,String s)
    {
        this.w=w;
        this.s=s;
    }
    public double getweight()
    {
        return w;
    }
}

package CumtJava;

public class Test {
    public static void main(String[] args) {

        Fruit[] f=new Fruit[3];
        f[0]=new Apple(100,"苹果");
        f[1]=new Peach(200,"桃子");
        f[2]=new Orange(300,"橘子");
        System.out.println("水果的类型和重量如下：");
        for(int i=0;i<3;i++)
        {
            System.out.println(f[i].getweight());
            System.out.println(f[i].getClass().getName());
        }
    }
}

2.3 运行截图