Java中5种方式实现String反转

//数组实现String反转  public String reverseByArray(){    if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串转换成字符数组    for(int i = 0 ; i < ch.length/2 ; i++){      char temp = ch[i];      ch[i] = ch[ch.length-i-1];      ch[ch.length-i-1] = temp;    }    return new String(ch);  }

//用栈实现String反转  public String reverseByStack(){    if(str == null || str.length() == 1){      return null;    }    Stack<Character> stack = new Stack<Character>();    char[] ch = str.toCharArray();//字符串转换成字符数组    for (char c : ch) {      stack.push(c);//每个字符，推进栈    }    for (int i = 0; i < ch.length; i++) {      ch[i] = stack.pop();//移除这个堆栈的顶部对象    }    return new String(ch);  }

//用逆序遍历实现String反转  public String reverseBySort(){    if(str == null || str.length() == 1){      return null;    }    StringBuffer sb = new StringBuffer();    for (int i = str.length() -1 ; i >= 0; i--) {      sb.append(str.charAt(i));//使用StringBuffer从右往左拼接字符    }    return sb.toString();  }

//使用位运算实现String反转  public String reverseByBit() {     if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串转换成字符数组    int len = str.length();     for(int i= 0; i< len/ 2; i++) {       ch[i]^= ch[len- 1- i];       ch[len- 1- i]^= ch[i];       ch[i]^= ch[len- 1- i];     }    return new String(ch);  }

//使用递归实现String反转  public String reverseByRecursive(String str){    if(str == null || str.length() == 0){      return null;    }    if(str.length() == 1){      return str;    } else {      //从下标为1开始截取字符串，在返回下标为0的字符      return reverseByRecursive(str.substring(1)) + str.charAt(0);    }  }

public class Test {  public static void main(String[] args) {    String s = "123456";    Reverse r = new Reverse(s);    System.out.println(r.reverseByArray());    System.out.println(r.reverseByStack());    System.out.println(r.reverseBySort());    System.out.println(r.reverseByBit());    System.out.println(r.reverseByRecursive(s));      }}

public class Reverse {  private String str = null;    public Reverse(String str){    this.str = str;  }    //数组实现String反转  public String reverseByArray(){    if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串转换成字符数组    for(int i = 0 ; i < ch.length/2 ; i++){      char temp = ch[i];      ch[i] = ch[ch.length-i-1];      ch[ch.length-i-1] = temp;    }    return new String(ch);  }  //用栈实现String反转  public String reverseByStack(){    if(str == null || str.length() == 1){      return null;    }    Stack<Character> stack = new Stack<Character>();    char[] ch = str.toCharArray();//字符串转换成字符数组    for (char c : ch) {      stack.push(c);//每个字符，推进栈    }    for (int i = 0; i < ch.length; i++) {      ch[i] = stack.pop();//移除这个堆栈的顶部对象    }    return new String(ch);  }  //用逆序遍历实现String反转  public String reverseBySort(){    if(str == null || str.length() == 1){      return null;    }    StringBuffer sb = new StringBuffer();    for (int i = str.length() -1 ; i >= 0; i--) {      sb.append(str.charAt(i));//使用StringBuffer从右往左拼接字符    }    return sb.toString();  }  //使用位运算实现String反转  public String reverseByBit() {     if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串转换成字符数组    int len = str.length();     for(int i= 0; i< len/ 2; i++) {       ch[i]^= ch[len- 1- i];       ch[len- 1- i]^= ch[i];       ch[i]^= ch[len- 1- i];     }    return new String(ch);  }  //使用递归实现String反转  public String reverseByRecursive(String str){    if(str == null || str.length() == 0){      return null;    }    if(str.length() == 1){      return str;    } else {      //从下标为1开始截取字符串，在返回下标为0的字符      return reverseByRecursive(str.substring(1)) + str.charAt(0);    }  }}