//數(shù)組實現(xiàn)String反轉  public String reverseByArray(){    if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串轉換成字符數(shù)組    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);  }

//用棧實現(xiàn)String反轉  public String reverseByStack(){    if(str == null || str.length() == 1){      return null;    }    Stack<Character> stack = new Stack<Character>();    char[] ch = str.toCharArray();//字符串轉換成字符數(shù)組    for (char c : ch) {      stack.push(c);//每個字符，推進棧    }    for (int i = 0; i < ch.length; i++) {      ch[i] = stack.pop();//移除這個堆棧的頂部對象    }    return new String(ch);  }

//用逆序遍歷實現(xiàn)String反轉  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從右往左拼接字符    }    return sb.toString();  }

//使用位運算實現(xiàn)String反轉  public String reverseByBit() {     if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串轉換成字符數(shù)組    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);  }

//使用遞歸實現(xiàn)String反轉  public String reverseByRecursive(String str){    if(str == null || str.length() == 0){      return null;    }    if(str.length() == 1){      return str;    } else {      //從下標為1開始截取字符串，在返回下標為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;  }    //數(shù)組實現(xiàn)String反轉  public String reverseByArray(){    if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串轉換成字符數(shù)組    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);  }  //用棧實現(xiàn)String反轉  public String reverseByStack(){    if(str == null || str.length() == 1){      return null;    }    Stack<Character> stack = new Stack<Character>();    char[] ch = str.toCharArray();//字符串轉換成字符數(shù)組    for (char c : ch) {      stack.push(c);//每個字符，推進棧    }    for (int i = 0; i < ch.length; i++) {      ch[i] = stack.pop();//移除這個堆棧的頂部對象    }    return new String(ch);  }  //用逆序遍歷實現(xiàn)String反轉  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從右往左拼接字符    }    return sb.toString();  }  //使用位運算實現(xiàn)String反轉  public String reverseByBit() {     if(str == null || str.length() == 1){      return null;    }    char[] ch = str.toCharArray();//字符串轉換成字符數(shù)組    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);  }  //使用遞歸實現(xiàn)String反轉  public String reverseByRecursive(String str){    if(str == null || str.length() == 0){      return null;    }    if(str.length() == 1){      return str;    } else {      //從下標為1開始截取字符串，在返回下標為0的字符      return reverseByRecursive(str.substring(1)) + str.charAt(0);    }  }}