Java-我如何使一个字符串读取并计算另一个字符串中的数量（

Question

我无法激活计数器++。到目前为止，s2能够读取s1，但不能计数出现的次数。如有任何帮助，我们将不胜感激。（我意识到我在错误的字符串中工作，但它帮助我首先在这里创建解决方案，然后将其发送到第二个字符串，这是不是很糟糕的逻辑？）

很抱歉问了这个愚蠢的问题，我对编程很陌生

//我需要一个扫描器来读取我所写内容，该扫描器应该计算一个字符的出现次数另一个扫描器声明的扫描器a会询问“write Something”字符串S。=nextline等新扫描器请求一个字母字符串s1=next line blb输入=something int count=StringUtils.countMatches(s1)；System.Out.Print（金额）i//

public class Task07 {

    public static void main(String[] args) {

        Scanner s1 = new Scanner(System.in);
        System.out.println("write something");
        String text = s1.nextLine(); //reads user input value

        Scanner s2 = new Scanner(System.in);  // missing smth that limits length of s2  
        System.out.println("geb a letter");
        String letter = s2.nextLine();
        int counter = 0;
        boolean found;
        found = text.contains(letter);
        if (found == true) {
            counter++;
        } else {

            System.out.println(counter);
        }
    // could use counter from 6 here but need a way to tell counter 
        // that it should add +1 for every time something occurs in 
        // the other scanner

        /*
            Problems: text recognizer is boolean only
             - doesnt activate counter
             - doesnt activate counter based on X times occurence           
            - doesnt limit "letter" to only one char
            - 

         */
    }

}

Answer 1

基本上，循环是计算字符串中字符出现次数的简单方法。您可以使用类似于

int counter = 0;
for (int i = 0; i < text.length(); i++) {
    if (text.charAt(i) == letter.charAt(0)) {
        counter++;
    }
}