java实现字符串反转

/**采用递归实现，将字符串分为前后两部分，颠倒**/
    public  String reverse1(String s) {
        int length = s.length();
        if (length <= 1)
            return s;
        String left = s.substring(0, length / 2);
        String right = s.substring(length / 2, length);
        return reverse1(right) + reverse1(left);
    }
    
    /**扫描一遍**/
    public  String reverse2(String s) {
        int length = s.length();
        String reverse = "";
        for (int i = 0; i < length; i++)
            reverse = s.charAt(i) + reverse;
        return reverse;
    }

    public  String reverse3(String s) {
        char[] array = s.toCharArray();
        String reverse = "";
        for (int i = array.length - 1; i >= 0; i--)
            reverse += array[i];

        return reverse;
    }

    public  String reverse4(String s) {
        return new StringBuffer(s).reverse().toString();
    }

    public  String reverse5(String s) {
        //char[] s = orig.toCharArray();
        int n = s.length() - 1;
        int halfLength = n / 2;
        for (int i = 0; i <= halfLength; i++) {
            char temp = s.charAt(i);
            s = this.Stringinsert(s , s.charAt(n-i),i);
            s = this.Stringinsert(s , temp , n-i);
        }
        return new String(s);
    }
    
    /**java-insert a char**/
    public String Stringinsert(String a,char b,int t){     
        return a.substring(0,t)+b+a.substring(t+1,a.length());
     }

    public  String reverse6(String s) {

        char[] str = s.toCharArray();

        int begin = 0;
        int end = s.length() - 1;

        while (begin < end) {
            str[begin] = (char) (str[begin] ^ str[end]);
            str[end] = (char) (str[begin] ^ str[end]);
            str[begin] = (char) (str[end] ^ str[begin]);
            begin++;
            end--;
        }

        return new String(str);
    }

    public  String reverse7(String s) {
        char[] str = s.toCharArray();
        Stack<Character> stack = new Stack<Character>();
        for (int i = 0; i < str.length; i++)
            stack.push(str[i]);

        String reversed = "";
        for (int i = 0; i < str.length; i++)
            reversed += stack.pop();

        return reversed;
    }