Test for the presence of only one hyphen in the account number

I would like to rewrite the following code using only String methods, without for loops.

// Run the QuestionGenerator and test for the error condition 
// indicated. If the account number has a valid format 
// according to the requirement set out in the question generator, return
// true, otherwise false.

private static boolean isAccountFormatCorrect(String name)  {
	int m = 0;
	for(int i = 0; i < name.length(); i++) {
		char a = name.charAt(i); 
		if (a == '-') { 
			m++; 
		}
	} 

	if (m >= 2) { 
		throw new BadAccountInputException("Only one hyphen allowed in account number");
	}
     
	return true;
}

Compare the first index of a hyphen with the last index where it is found. If they are equal, then there was only one.

private static boolean isAccountFormatCorrect(String name)  {
    if(name.indexOf('-') != name.lastIndexOf('-')){
      throw new BadAccountInputException("Only one hyphen allowed in account number");
    }
    return true;
}

However, it seems you want to return a boolean indicating whether or not the account is valid, in which case there is no need to throw exceptions.

private static boolean isAccountFormatCorrect(String name)  {
    return name.indexOf('-') == name.lastIndexOf('-');
}

If you need to ensure there exactly one hyphen, you will need to check that the index of not -1.

private static boolean isAccountFormatCorrect(String name)  {
    int idx = name.indexOf('-');
    return idx != -1 && idx == name.lastIndexOf('-');
}