LeetCode 520 Detect Capital

import org.junit.Test;

/**
 * @Description 520：https://leetcode.com/problems/detect-capital/
 * @Author zlb
 * @Date 2019/7/2 10:50
 **/
public class DetectCapital {

    public boolean detectCapitalUse(String word) {
        int length = word.length();
        char[] charArray = word.toCharArray();
        String firstLetter = "";
        int upperNum = 0;
        for (int i=0; i<length; i++) {
            String result = upperOrLower(charArray[i]);
            if (i==0) {
                firstLetter = result;
            }
            if ("upper".equals(result)) {
                upperNum++;
            }
        }
        if (upperNum == 0 || upperNum == length || (upperNum ==1 && "upper".equals(firstLetter))) {
            return true;
        }
        return false;
    }

    private String upperOrLower(char c) {
        if (c >= 'A' && c <= 'Z') {
            return "upper";
        }
        return "lower";
    }

    @Test
    public void test() {

        // String word = "Flag";
        // String word = "leetcode";
        String word = "USA";
        System.out.println(detectCapitalUse(word));

    }

}