设计要求

编写程序模拟两个村庄共同拥有一片森林；编写一个Village类，该类有一个静态的int型成员变量treeAmount用于模拟森林中树木的数量；在主类MainClass的main方法中创建了两个村庄，一个村庄改变了treeAmount值，另一个村庄查看treeAmount值。

设计流程图

程序代码

类Village代码

package com.yuan;

public class Village {
        static int treeAmount;
        //模拟森林中树木的数量
        String name;
        Village(String s){
            name=s;
        } //含参构造
        void treePlanting(int n){
            treeAmount=treeAmount+n;
            System.out.println(name+"村植树"+n+"棵后");
        }
        //植树
        void fellTree(int n){
            if(treeAmount-n>=0){
                treeAmount=treeAmount-n;
                System.out.println(name+"村伐树"+n+"棵后");
            }
            else{
                System.out.println("森林里没有树了！！！");
            }
        }
        static int lookTreeAmount() {
            return treeAmount;
        }
}

类MainClass代码

package com.yuan;
public class MainClass {
    public static void main(String[] args) {
        Village xiaohe, dahe;
        xiaohe = new Village("小河");
        dahe = new Village("大河");
        Village.treeAmount = 200;
        int leftTree = Village.treeAmount;
        System.out.println("森林中有" + leftTree + "棵树");
        dahe.treePlanting(50);
        System.out.println("大河村植树50棵后");
        leftTree = Village.lookTreeAmount();
        System.out.println("森林中有" + leftTree + "棵树");
        dahe.fellTree(70);
        leftTree = Village.lookTreeAmount();
        System.out.println("森林中有" + leftTree + "棵树");
       }
}

可以直接运行的代码

package com.yuan;
//这个包是自己建立的，所以如果引入不了的话就不用引用了，自己建一个
public class Village {
        static int treeAmount;
        //模拟森林中树木的数量
        String name;
        Village(String s){
            name=s;
        } //含参构造
        void treePlanting(int n){
            treeAmount=treeAmount+n;
            System.out.println(name+"村植树"+n+"棵后");
        }
        //植树
        void fellTree(int n){
            if(treeAmount-n>=0){
                treeAmount=treeAmount-n;
                System.out.println(name+"村伐树"+n+"棵后");
            }
            else{
                System.out.println("森林里没有树了！！！");
            }
        }
        static int lookTreeAmount() {
            return treeAmount;
        }
    public static void main(String[] args) {
        Village xiaohe, dahe;
        xiaohe = new Village("小河");
        dahe = new Village("大河");
        Village.treeAmount = 200;
        int leftTree = Village.treeAmount;
        System.out.println("森林中有" + leftTree + "棵树");
        dahe.treePlanting(50);
        System.out.println("大河村植树50棵后");
        leftTree = Village.lookTreeAmount();
        System.out.println("森林中有" + leftTree + "棵树");
        dahe.fellTree(70);
        leftTree = Village.lookTreeAmount();
        System.out.println("森林中有" + leftTree + "棵树");
    }
}