使用Java递归地计算父子关系中文件夹中的邮件数量？

import java.io.File;

public class EmailCounter {
    public static int countEmails(String folderPath) {
        int count = 0;
        File folder = new File(folderPath);
        
        if (folder.isDirectory()) {
            File[] files = folder.listFiles();
            
            if (files != null) {
                for (File file : files) {
                    if (file.isFile()) {
                        String fileName = file.getName();
                        if (fileName.endsWith(".eml")) {
                            count++;
                        }
                    } else if (file.isDirectory()) {
                        count += countEmails(file.getAbsolutePath());
                    }
                }
            }
        }
        
        return count;
    }
    
    public static void main(String[] args) {
        String folderPath = "path/to/parent/folder";
        int emailCount = countEmails(folderPath);
        System.out.println("Total email count: " + emailCount);
    }
}