Java 中给定字符在数组中的出现次数

Question

这是我的作业，我试图获取数组字符串中“e”的出现次数。我的方法好像不行。任何明智的人都可以告诉我哪里出了问题吗？

import java.util.*;
import java.lang.*;
import java.io.*;

public class CountChar {
    public static void main(String[] args) {
        String[] strings
                = {"hidden", "Java SDK", "DDD", "parameter", "polymorphism", "dictated", "dodged", "cats and dogs"};
        int result = numberOfCharacters(strings, 'e');
        System.out.println("No. of occurrences of 'e' is " + result);
    }

    public static String numberOfCharacters(String str, char a) {
        int aresult = 0;
        if (str.length() > 0) {
            aresult = count(str.substring(1), a) + (str.charAt(0) == a ? 1 : 0);
        }
        return aresult;
    }    
}

Answer 1

只需将方法签名更改为:

public static String numberOfCharacters(String[] str, char a) {

///code
}