java - 方法不允许返回字符串

Question

我有一个递归生成随 secret 码的方法，要求至少有一个大写字母。我已经设置了方法，但出于某种原因，当我已经在我的 if 语句中定义了 return 类型时，它告诉我该方法必须返回 String 类型。

问题:如何消除此错误或修复我的方法以使其返回密码？

public static char[]chars = {'a','b','c','d','e','f','g','h','i','j','k','l','m',
                'n','o','p','q','r','s','t','u','v','w','x','y','z','0','1','2','3','4','5',
                '6','7','8','9','!','@','$','%','^','&'};

            public static String generatePassword(Random rand, String password, int position, int size) //this method must return a result of type String
            {
                boolean isLowerCase = rand.nextBoolean();
                int randomChar = rand.nextInt(chars.length);
                char c = chars[randomChar];
                if(position == size) //base case
                {
                    return password; //string is returned here? 
                }
                if(isLowerCase)
                {
                    generatePassword(rand, password + c, position + 1, size);
                }
                else //its either upper or lower case
                {
                    generatePassword(rand, password + Character.toUpperCase(c), position + 1, size);
                }

Answer 1

在您的所有执行组合的方法中，应该返回一个字符串。您的方法应如下所示。

    public static String generatePassword(Random rand, String password, int position, int size) //this method must return a result of type String
    {
        boolean isLowerCase = rand.nextBoolean();
        int randomChar = rand.nextInt(chars.length);
        char c = chars[randomChar];
        if(position == size) //base case
        {
            return password; //string is returned here? 
        }
        if(isLowerCase)
        {
            return generatePassword(rand, password + c, position + 1, size);
        }
        else //its either upper or lower case
        {
            return generatePassword(rand, password + Character.toUpperCase(c), position + 1, size);
        }
     }