day04-Scanner

Scanner类

package com.fang.scanner;
import java.util.Scanner;

public class Demo02 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        //请输入整数
        System.out.println("请输入整数:");
        if(scanner.hasNextInt()){
            int i1 = scanner.nextInt();
            System.out.println("整数数据"+i1);
        }else {
            System.out.println("输入的不是整数");
        }
        //请输入小数
        System.out.println("请输入小数:");
        if(scanner.hasNextFloat()){
            float f1 = scanner.nextFloat();
            System.out.println("小数数据"+f1);
        }else {
            System.out.println("输入的不是小数");
        }
        scanner.close();
    }
}

例题

package com.fang.scanner;

import java.util.Scanner;

public class Demo03 {
    //计算学生成绩的总和和平均数
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int num = 0;
        double sum = 0.0;
        System.out.println("请输入学生成绩:");
        while (scanner.hasNextDouble()){
            double score = scanner.nextDouble();
            num ++;
            sum += score;
            System.out.println("第"+num+"个学生成绩为:"+score);
        }
        System.out.println(num+"个数据的和为："+sum);
        System.out.println(num+"个数据的平均成绩为:"+(sum/num));
        scanner.close();
    }
}