LeetCode 709. 转换成小写字母

package string;

/**
 * Created with IntelliJ IDEA.
 * Version : 1.0
 * Author  : cunyu
 * Email   : cunyu1024@foxmail.com
 * Website : https://cunyu1943.github.io
 * Date    : 2020/4/3 17:45
 * Project : LeetCode
 * Package : string
 * Class   : SevenZeroNight
 * Desc    :
 */
public class SevenZeroNight {
	public static void main(String[] args) throws Exception {
		String str = "Hello World!";
		SevenZeroNight sevenZeroNight = new SevenZeroNight();
		System.out.println(sevenZeroNight.toLowerCase(str));
	}

	public String toLowerCase(String str) {
		String resultStr = "";
		for (int i = 0; i < str.length(); i++) {
			int ch = (int) str.charAt(i);
			if ((int) ch >= 65 && (int) ch <= 90) {
				ch += 32;
			}
			resultStr += "" + (char) ch;
		}
		return resultStr;
	}
}