Rotate String

题目
Given two words, find if second word is the round rotation of first word.
For example: abc, cab
return 1
since cab is round rotation of abc

Example2: ab, aa
return -1
since ab is not round rotation for aa

Idea: 如果是经过翻转所得，那么先连接word1 + word1，然后判断是否包含word2即可。

import java.lang.String;

public class RorateString {

    public static int isRotation(String word1, String word2) {
        if (word1 == null || word2 == null || word1.length() == 0 || word2.length() == 0 || word1.length() != word2.length()) {
            return -1;
        }
        String str = word1 + word1;
        return str.indexOf(word2) != -1 ? 1 : -1;
    }
}