Java 讀取輸入字符和字符串

1. 使用Scanner讀取字符和字符串

/**
 * Created by SheepCore on 2020-2-26
 */
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in); //聲明一個Scanner對象，初始輸入流為控制台
        String name = scan.nextLine(); //讀取鍵盤輸入字符串（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(); //讀取下一個int(光標停在本行的空格之前）
        height = scan.nextFloat(); //讀取下一個float
        weight = scan.nextDouble(); //讀取下一個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()讀取單個字符

如果只要讀取一個字符可以通過read()方法實現。

/**
 * 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 {  //如果輸入有誤或者沒有輸入則會拋出IOException，所以這里需要在try_catch_block中捕獲
            read = (char) System.in.read(); //通過控制台讀取一個字符
            System.out.println(read);
        } catch(Exception e) {
            e.printStackTrace(); //打印錯誤信息
        }
    }
}

3. 通過BufferedReader以緩沖方式讀取字符串

這種方法可以讀取一行中的空格(space and tab)，而Scanner讀取時按空格分隔，空格后面無法讀取，如果想要讀取含有空格的字符串就需要使用這種方法。

/**
 * 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:

這三種方法幾乎可以應對所有的控制台輸入，如果想多行輸入，只需使用循環控制語句多次輸入就可以了！掌握這些就可以開啟刷題之旅了! Let's go get LeetCode!

 

水滴石穿，笨鳥先飛！