剑指Offer 42题 左旋转字符串 Java版

package test;public class ReverseSentenceUpdate {public String reverse(String sentence){if(sentence == null || "".equals(sentence)){return null;}String string = "";for(int i=0; i<sentence.length(); ++i){string =sentence.charAt(i)+""+string;}return string;}public void leftRotateString(String word,int n){String before = word.substring(0, n);String end = word.substring(n);before = reverse(before);end = reverse(end);before = before+end;before = reverse(before);System.out.println(before);}public static void main(String[] args) {// TODO Auto-generated method stubString string = "abcdefg";int n = 2;ReverseSentenceUpdate reverseSentenceUpdate = new ReverseSentenceUpdate();reverseSentenceUpdate.leftRotateString(string, n);}}