Count the number of occurrences of letters in a string

describe:

Given a string, randomly enter a letter and determine the number of times the letter appears in the string.

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Enter description:

First line: a string.

Second line: any letter.

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Output description:

The number of times a letter appears in a string.

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Example

enter:

H e l l o ! n o w c o d e r

O

Output:

3

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the first method 

Code:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        String string = scanner.nextLine();//nextLine()可以输入空格，遇到回车就断了
        String word = scanner.nextLine();
        scanner.close();
        System.out.println(check(string, word));
    }

    public static int check(String str, String word) {
        return str.length() - str.replace(word,"").length();//用字符串中的replace替代方法将输入的字母在原字符串中替换为空，这样用原字符串的长度-现在的字符串长度就是所求字母出现的次数。
    }
}

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The second method 

Code:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        String string = scanner.nextLine();//nextLine()可以输入空格，遇到回车就断了
        String word = scanner.nextLine();
        scanner.close();
        System.out.println(check(string, word));
    }

    public static int check(String str, String word) {

         char c = word.charAt(0); //将第二个字符串用字符表示
        int count = 0;
        for(int i = 0; i < str.length(); i++) //遍历第一个字符串
            if(c == str.charAt(i)) //比较每个字符与c是否相同
                count++; //相同则计数
        return count;
    }
}

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Summary: Learn to use the replace method reasonably.​