【Java】Scanner的常用方法(一次学懂)

Scanner类是一个可以帮助用户键盘输入内容的一个类。

一.基本的Scanner输入

①输入整数、小数

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int a = scanner.nextInt();
		double b = scanner.nextDouble();
		System.out.println(a);
		System.out.println(b);
	}
}

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②输入一维数组

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();//定义数组长度为n
		int[] arr = new int[n];//定义一个长度为n，名叫arr的数组
		for (int i = 0; i < n; i++) {
			arr[i]=scanner.nextInt();
		}
		System.out.print("Scanner输入的数组为:");
		for (int i = 0 ; i < n ; i++) {
			System.out.print(arr[i]+" ");			
		}
	}
}

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输入二维数组

import java.util.Scanner;

public class Test2 {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		int m = scanner.nextInt();
		int[][] mat = new int[n][m];
		System.out.println("请输入整数型的二维数组:");
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				mat[i][j]=scanner.nextInt();
			}
		}
		for (int i = 0; i < n; i++) {
			System.out.print("[");
			for (int j = 0; j < m; j++) {
				if(j==m-1) {
					System.out.print(mat[i][j]);
				}else {
					System.out.print(mat[i][j]+",");
				}
			}
			System.out.print("]");
			System.out.println();
		}
	}
}

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③输入字符串数组

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		String[] arr = new String[n];
		for(int i = 0 ; i < n ; i ++) {
			arr[i]=scanner.next();
		}
		System.out.println("输入的字符串数组为:");
		for (int i = 0; i < arr.length; i++) {
			System.out.print(arr[i]);
		}
		
	}
}

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 二.例【猜数字】

创建ScannerDemo类，首先在主方法中创建一个随机数，然后再创建一个while循环不断获取用户输入的数字，让用户输入的数字与随机数比较，给出“大于”或“小于”的提示，直到用户输入的数字与随机数相等才结束循环。

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

public class ScannerDemo {
	public static void main(String[] args) {
		Random r = new Random();
		int num = r.nextInt(100);
		int input = -1;
		Scanner scanner = new Scanner(System.in);
		while(true) {
			System.out.println("猜一猜随机数是多少？");
			input=scanner.nextInt();
			if (input>num) {
				System.out.println("你输入的数字大了！");
			}else if(input

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