Java基础--Scanner类

Scanner类:

Java5: java.util.Scanner包
基础语法：Scanner s = new Scanner(System.in);

package Scanner;
import java.util.Scanner;

public class Demo01 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("使用next方法接收：");
        if (scanner.hasNext()){
            String str = scanner.next();
            System.out.println("输入的内容为:" + str);
        }
        // 凡是属于IO流的类，如果不关闭会一直占用资源，养成良好的习惯。
        scanner.close();
    }
}

package Scanner;
import java.util.Scanner;

public class Demo02 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("使用nextLine方法接收：");
        if (scanner.hasNextLine()){
            String  str = new String();
            str = scanner.nextLine();
            System.out.println("输入的内容为:" + str);
        }
        scanner.close();
    }
}

package Scanner;

import java.util.Scanner;

public class Demo04 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int i = 0;
        float f = 0.0f;

        System.out.println("请输入整数：");
        if(scanner.hasNextInt()){
            i = scanner.nextInt();
            System.out.println("整数数据："+i);
        }else{
            System.out.println("输入的不是整数数据。");
        }
        System.out.println("请输入小数：");
        if(scanner.hasNextFloat()){
            f = scanner.nextFloat();
            System.out.println("小数数据："+f);
        }else{
            System.out.println("输入的不是浮点数据。");
        }
    }
}

package Scanner;

import java.util.Scanner;

public class Demo05 {
    public static void main(String[] args) {
        // 输入多个数字，求和和平均数
        Scanner scanner = new Scanner(System.in);
        double sum = 0;
        int n = 0;
        while(scanner.hasNextDouble()){
           double x = scanner.nextDouble();
            n++;
            sum += x;
        }
        System.out.println("总和："+ sum);
        System.out.println("平均数:"+ (sum /n));
        System.out.println();
        scanner.close();
    }
}