Length of Last Word on LeetCode

LengthOfLastWord.java

package leetcode.stringSimple;

/**
 *  Method 1: General way, remeber to check if count =0 when meet " "
 *  Do I need to change first condition to (str[i]!= ' ') ? I think it doesn't matter.
 * 
 * 
 *  Method 2: " ".isEmpty()  " ".length()  == false!!!  If we use this way, we must include s.trim().isEmpty() at first. 
 *  Or, it will splited as String[] arr, the length of arr equals to 0, so there will be a ArrayOutofBound Exception.
 * 
 *  Test case: "  " ,  "Hello World  "  
 * 
 */

public class LengthOfLastWord {

	// test case: Str may end up with '' -- most important part 

	public static void main(String args[]) {
		System.out.println(lengthOfLastWord2(" "));
	}
	
	public static int lengthOfLastWord(String s) {
		if (s == null || s.length() == 0) {
			return 0;
		}

		char[] str = s.toCharArray();

		int count = 0;
		for (int i = str.length - 1; i >= 0; i--) {
			
			if ((str[i] >= 'a' && str[i] <='z') || (str[i] >= 'A' && str[i] <= 'Z')) {
				count++;
			}

			if (str[i] == ' ') {
				if (count == 0) {
					continue; 
				} else {
					// have already go through a word
					return count;
				}
			}
		}
		
		return count;
	}
	
	private static int lengthOfLastWord2(String s) {
		// if s = " ", s.isEmpty == false because there's a blank!   
		if (s == null || s.length() == 0 || s.trim().isEmpty()) {
			return 0;
		}
		
		String[] arr = s.split(" ");
		return arr[arr.length - 1].length();
	}

	
}