用个StringBuilder对字符串进行拼接即可
public String LeftRotateString(String str,int n) { if (str.equals("")||str==null) { return ""; }else { String lastStr=str.substring(0,n); StringBuilder sb=new StringBuilder(str.substring(n)); sb.append(lastStr); return sb.toString(); } }
原文：https://www.cnblogs.com/Transkai/p/11375516.html