java小案例

Scanner类计算

package com.demo;

import java.util.Scanner;	//导入包

public class hello {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);	//使用类先创建对象
        System.out.println("请输入第一个数：");
        int i = sc.nextInt();					//接受数据并赋值
        System.out.println("请输入第二个数：");
        int i1 = sc.nextInt();

        int num = i +i1;

        System.out.println("结果：" + num);
    }
}

for循环输出五次

package com.demo;

public class hello {

    public static void main(String[] args) {
        for(int i = 1;i <= 5;i++){
            System.out.println("你好！");
        }
    }
}

while循环输出五次

package com.demo;

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

        int i = 1;
        while (i <= 5){
            System.out.println("你好！");
            i++;
        }
    }
}

复读机

package com.demo;

import java.util.Scanner;

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

        Scanner sc = new Scanner(System.in);
        while (true) {
        String i = sc.next();
        System.out.println(i);
        }
    }
}

逢7必过小游戏

package com.demo;

public class hello {

    public static void main(String[] args) {
    
        for (int i = 1;i<=100;i++ ){							//循环100的数字
        
            if(i%10 == 7 || i/10%10 == 7 || i%7 == 0){			
            //除10余7、除10后除10余7、除7等于0
                System.out.println("...");
                continue;
                //跳出继续循环
            }
            System.out.println(i);								//输出100的数字
        }
    }
}

猜数字小游戏

package com.demo;

import java.util.Random;
import java.util.Scanner;

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

        Random r = new Random(); 						//创建对象

        int num = r.nextInt(100) + 1;					//1-100随机数

        Scanner sc = new Scanner(System.in);

        while (true){
            System.out.println("请输入你才得数字：");
            int i = sc.nextInt();						//输入数字

            if(i > num){
                System.out.println("大");
            }else if(i < num){
                System.out.println("小");
            }else {
                System.out.println("猜对了");
                break;
            }
        }
    }
}

调用方法

package com.demo;

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

        int x = num(1,2);
        System.out.println(x);
    }

    public static int num(int a,int b) {
        int c = a+b;
        return c;
    }
}

获取int最大的值

package com.demo;

public class hello {

    public static void main(String[] args){
        int[] arr = {1,2,3,5,9};

        int temp = arr[0];

        for (int i = 0;i < arr.length;i++){
            if(arr[i]>temp){
                temp = arr[i];
            }
        }
        System.out.println(temp);
    }
}

计算器

package com.demo;

import java.util.Scanner;

public class ww{
    public static void main(String[] args) {
        // 创建键盘录入对象
        Scanner sc = new Scanner(System.in);

        System.out.println("请输入一个整数：");
        // 接收数据
        int i = sc.nextInt();
        System.out.println("请输入第二个整数：");
        int f = sc.nextInt();

        System.out.println("请输入计算符号(+ - * /)：");

        String s = sc.next();

        int result = 0;
        switch (s) {
            case "+":
                result = i + f;
                break;
            case "-":
                result = i - f;
                break;
            case "*":
                result = i * f;
                break;
            case "/":
                result = i / f;
                break;
            default:
                System.out.println("计算结果：" + (i + f));
        }

        System.out.println("计算结果：" + result);
    }
}

斗地主

package com.demo;

import java.util.*;

public class length {
    public static void main(String[] args) {
        //定义一个双列集合
        Map<Integer,String> pokers = new HashMap<>();
        //定义一个单列集合，用来存储所有牌得编号
        List<Integer> list = new ArrayList<>();
        //具体买牌
        String[] colors = {"♠","♥","♣","♦"};
        String[] numbers = {"3","4","5","6","7","8","9","10","J","Q","K","A","2"};
        //循环嵌套(外：获取点数、内：获取花色)
        int num = 0;
        for (String number : numbers){
            for (String color : colors){
                String poker = color + number;
                //将牌得编号放到单列集合中
                pokers.put(num, poker);
                //将牌得编号放到单列集合中
                list.add(num);
                //加1
                num++;
            }
        }
        //大王
        pokers.put(num,"大王");
        list.add(num++);
        //小王
        pokers.put(num,"大王");
        list.add(num++);
        //洗牌
        Collections.shuffle(list);
        //定义四个集合、表示玩家
        List<Integer> liu = new ArrayList<>();
        List<Integer> wang = new ArrayList<>();
        List<Integer> zhang = new ArrayList<>();
        List<Integer> die = new ArrayList<>();
        //具体发牌动作
        for (int i = 0;i < list.size();i++){
            Integer pokerNum = list.get(i);
            if (i >= list.size() - 3){
                die.add(pokerNum);
            }else if (i % 3 == 0){
                liu.add(pokerNum);
            }else if (i % 3 == 1){
                wang.add(pokerNum);
            }else if (i % 3 == 2){
                zhang.add(pokerNum);
            }
        }
        String str = printPoker(liu,pokers);
        System.out.println("liu：" + printPoker(liu,pokers));
        System.out.println("wang：" + printPoker(wang,pokers));
        System.out.println("zhang：" + printPoker(zhang,pokers));
        System.out.println("die：" + die);
    }
    /*
    定义一个方法，用来看牌
    方法名：printPoker
    参数列表：List<Integer>,Map<Integer,String>
    返回值：String
    */
    public static String printPoker(List<Integer> nums,Map<Integer,String> pokers) {
        //对牌的编号进行升序排列
        Collections.sort(nums);
        //遍历牌的编号集合、获取到每一个编号
        StringBuilder sb = new StringBuilder();
        for (Integer num :nums){
            //num就是要查找的具体牌的编号
            String poker = pokers.get(num);
            //将获取到的牌进行拼接
            sb.append(poker + " ");
        }
        //将最后拼接结果返回即可
        String str = sb.toString();
        return str.trim();
    }
}