Java 读取输入字符和字符串

1. 使用Scanner读取字符和字符串

/**
 * Created by SheepCore on 2020-2-26
 */
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in); //声明一个Scanner对象，初始输入流为控制台
        String name = scan.nextLine(); //读取键盘输入字符串（包括空格、Tab，不包括最后的Enter)
        String id = scan.nextLine();
        int age;
        float height;
        double weight;
        age = scan.nextInt(); //读取下一个int(光标停在本行的空格之前）
        height = scan.nextFloat(); //读取下一个float
        weight = scan.nextDouble(); //读取下一个double

        System.out.println("name: " + name + "\nid: " + id);
        System.out.println("age: " + age + " height: " + height + " weight: " + weight);
    }
}

sheepcore
11001100
22 178.3 68.5
name: sheepcore
id: 11001100
age: 22 height: 178.3 weight: 68.5

 

2. 使用System.in.read()读取单个字符

如果只要读取一个字符可以通过read()方法实现。

/**
 * Created by SheepCore on 2020-2-26
 */

public class Main {
    public static void main(String[] args) {
        char read;
        System.out.print("Enter a char:  ");
        try {  //如果输入有误或者没有输入则会抛出IOException，所以这里需要在try_catch_block中捕获
            read = (char) System.in.read(); //通过控制台读取一个字符
            System.out.println(read);
        } catch(Exception e) {
            e.printStackTrace(); //打印错误信息
        }
    }
}

3. 通过BufferedReader以缓冲方式读取字符串

这种方法可以读取一行中的空格(space and tab)，而Scanner读取时按空格分隔，空格后面无法读取，如果想要读取含有空格的字符串就需要使用这种方法。

/**
 * Created by SheepCore on 2020-2-26
 *
 * how to deal with BufferedReader
 * try and catch the IOException
 * read a line with readLine()
 */
public class Main {
    public static void main(String[] args) {
        String name;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.print("What's your name?  ");
        try {
            name =  br.readLine();
            System.out.println("My name is " + name + ".");
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}

What's your name?  Sheep Core
My name is Sheep Core.

 

4.Summary:

这三种方法几乎可以应对所有的控制台输入，如果想多行输入，只需使用循环控制语句多次输入就可以了！掌握这些就可以开启刷题之旅了! Let's go get LeetCode!

 

水滴石穿，笨鸟先飞！