java实现字符串反转

import java.util.Stack;public class StringReverse {  // 使用内置类(StringBuilder或StringBuffer)  public static String reverse1(String s) {    // StringBuilder strBuilder = new StringBuilder(s);    // String ret = strBuilder.reverse().toString();    StringBuffer strBuf = new StringBuffer(s);    String ret = strBuf.reverse().toString();    return ret;  }  // 有左到右 拼接字符串  public static String reverse2(String s) {    String ret = "";    for (int i = 0; i < s.length(); ++i) {      ret = s.charAt(i) + ret;    }    return ret;  }  // 从右到左 拼接字符串  public static String reverse3(String s) {    String ret = "";    for (int i = s.length() - 1; i >= 0; --i) {      ret += s.charAt(i);    }    return ret;  }  public static String reverse4(String s) {    String ret = "";    char[] charArr = s.toCharArray();    int len = charArr.length;    for (int i = 0; i < len / 2; ++i) {      char tmp = charArr[i];      charArr[i] = charArr[len - 1 - i];      charArr[len - 1 - i] = tmp;    }    ret = new String(charArr);    return ret;  }  // 使用异或  public static String reverse5(String s) {    String ret = "";    char[] charArr = s.toCharArray();    int begin = 0, end = charArr.length - 1;    while (begin < end) {      charArr[begin] = (char) (charArr[begin] ^ charArr[end]);      charArr[end] = (char) (charArr[begin] ^ charArr[end]);      charArr[begin] = (char) (charArr[begin] ^ charArr[end]);      begin++;      end--;    }    ret = new String(charArr);    return ret;  }  // 使用栈  public static String reverse6(String s) {    String ret = "";    Stack<Character> stack = new Stack<Character>();    for (int i = 0; i < s.length(); ++i) {      stack.push(s.charAt(i));    }    while (!stack.isEmpty()) {      ret += stack.pop();    }    return ret;  }}