Cannot get these regex matches to work correctly. How do I do this?

I am attempting to make a program run for homework. I have all of the other code written for the gui that everything is displayed in, but we are required to do checks on the input by using Regex's and going to see if they match. I need to check and make sure that there are 6 numbers 0-99 inclusive that are all separated by 1 or more spaces with no spaces at the beginning or end of the string.

The inputValidation method is where I am doing these checks. This is the code that I have so far.

    public String computeSum(String numbers) {
        String errorMessage = validateInput(numbers);
        if (!errorMessage.isEmpty()) {
            return errorMessage;
        }
        int sum = 0;
        String[] nums = numbers.split("\s+");
        for (int i = 0; i < nums.length; i++) {
            sum += Integer.parseInt(nums[i]);
        }
        return "" + sum;
    }

    public String validateInput(String numbers) {
        // Check if the input is empty
        if (numbers == null || numbers.isEmpty()) {
            return "Error: Input cannot be empty";
        }

        // Check if there are any spaces before the first number or after the last number
        if (!numbers.matches("^(?!\\s)\\d{1,2}( \\d{1,2})*(?!\\s)$")) {
            return "Error: Cannot have spaces before the first number or after the last number";
        }
        // Check if all numbers are between 0 and 99 inclusive
        else if (!numbers.matches("^(\\d{1,2} ){5}\\d{1,2}$")) {
            return "Error: All numbers must be between 0 and 99 inclusive";
        }
        else
        {
         return "";   
        }

Any help would be appreciated.

I don't really know why my regex's aren't being detected correctly. Currently the "Check if there are any spaces before the first number or after the last number" check is going off correctly, but if I have a number that is greater than 99 inclusive, it shoots the same error message rather than the correct one with the specific check that I made.

Use this code:

public static String validateInput1(String numbers) {
	// Check if the input is emptyXj
	if (numbers == null || numbers.isEmpty()) {
		return "Error: Input cannot be empty";
	}

	// Check if there are any spaces before the first number or after the last
	// number
	if (numbers.matches("^\\s+\\d{1,2}(\\s+\\d{1,2}){5}$") 
			|| numbers.matches("^\\d{1,2}(\\s+\\d{1,2}){5}\\s+$")
			|| numbers.matches("^\\s+\\d{1,2}(\\s+\\d{1,2}){5}\\s+$")) {
		return "Error: Cannot have spaces before the first number or after the last number";
	}
	// Check if all numbers are between 0 and 99 inclusive
	else if (!numbers.matches("^\\d{1,2}(\\s+\\d{1,2}){5}$")) {
		return "Error: All numbers must be between 0 and 99 inclusive";
	} else {
		return "";
	}
}

Reason
For the "Check if there are any spaces before the first number or after the last number", you used if (!numbers.matches("^(?!\\s)\\d{1,2}( \\d{1,2})*(?!\\s)$"))

• First numbers.matches("^(?!\\s)\\d{1,2}( \\d{1,2})*(?!\\s)$")
  returns false because nothing is captured and as nothing gets captured it returns false and always gives Error: Cannot have spaces before the first number or after the last number
• Second (!numbers.matches("^(\\d{1,2} ){5}\\d{1,2}$")) is working fine but numbers.matches("^(\\d{1,2} ){5}\\d{1,2}$") will return as false for any 2 numbers seperated by more than one space which will give Error: All numbers must be between 0 and 99 inclusive

Also .matches(String regex) matches the whole string not a part of it so for the space check I have used

numbers.matches("^\\s+\\d{1,2}(\\s+\\d{1,2}){5}$") || numbers.matches("^\\d{1,2}(\\s+\\d{1,2}){5}\\s+$") || numbers.matches("^\\s+\\d{1,2}(\\s+\\d{1,2}){5}\\s+$")

So use the above code.