Java面试题一

java基础练习：变量、数据类型、输入、输出、运算符

练习1：判断输入的值是否是偶数，另外，要处理输入错误

package com.mhg;

import java.util.Scanner;

/**
 * @Time :2022/2/10 13:01
 * @Author :MHG
 **/
public class TestDay01 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("请输入一个整数：");
        // 判断是否输入了一个整数
        if (input.hasNextInt()) { // 如果输入的是整数，则返回true,否则返回false
            int num = input.nextInt();
            if (num%2 == 0) {
                System.out.println(num + "是偶数");
            }else{
                System.out.println(num + "是奇数");
            }
        }else {
            System.out.println("输入无效！");
        }
    }
}

练习2：输入并输出姓名、年龄、身高

package com.mhg;

import java.util.Scanner;
/**
 * @Time :2022/2/11 13:23
 * @Author :MHG
 **/
public class TestDay02 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.println("请输入姓名：");
        String name = input.next();
        System.out.println("请输入年龄：");
        int age = input.nextInt();
        System.out.println("请输入身高：");
        Double height = input.nextDouble();
        System.out.println("姓名是：" + name);
        System.out.println("年龄是：" + age);
        System.out.println("身高是：" + height);
    }
}

练习3：从控制台获取Java、Oracle、HTML三门课程的成绩，计算总分和平均分（平均分保留2位小数，要求四舍五入）

package com.mhg;

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

/**
 * @Time :2022/2/12 13:33
 * @Author :MHG
 **/
public class TestDay03 {
    public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
        System.out.println("请输入JAVA成绩： ");
    float java = scanner.nextFloat();
        System.out.println("请输入Oracle成绩： ");
    float oracle = scanner.nextFloat();
        System.out.println("请输入HTML成绩： ");
    float html = scanner.nextFloat();
        System.out.println("-----------------------------");
        System.out.println("Java  Oracle  Html");
        System.out.println((int) java + "      "  + (int) oracle + "     " +(int) html);
        System.out.println("-----------------------------\n");
    float sum = java + oracle + html;
    float avg = sum / 3;
        System.out.println("总分：" + sum);
        System.out.println("平均分：" + new DecimalFormat("###.00").format(avg));
    }
}

练习4：输入一个数字，反转输出，如：输入123，输出321

package com.mhg;

import java.util.Scanner;

/**
 * @Time :2022/2/13 13:38
 * @Author :MHG
 **/
public class TestDay04 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("请输入一个整数：");
        if (input.hasNextInt()) {
            int num = input.nextInt();
            while (num != 0) {
                int res = num % 10;
                System.out.print(res);
                num = num / 10;
            }
        } else {
            System.out.println("输入有误！");
        }
    }
}

练习5：输入tom和jack的年龄，比较年龄并输出相差多少岁，要求使用条件运算符

package com.mhg;

import java.util.Scanner;

/**
 * @Time :2022/2/13 13:46
 * @Author :MHG
 **/
public class TestDay05 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入tom的年龄: ");
        int tomAge = scanner.nextInt();
        System.out.println("请输入jack的年龄: ");
        int jackAge = scanner.nextInt();
        int diff = tomAge - jackAge;
        if(diff == 0)
            System.out.println("tom和jack一样大");
        else{
            String status = diff > 0 ? "大" : "小";
            System.out.println("tom比jack" + status + Math.abs(diff) + "岁");
        }

    }
}