编程珠玑第二章之旋转算法

通过reverse实现字符串的旋转

public String reverseTarget(String str,int index){
        StringBuilder qian = reverse(str.substring(0, index));
        StringBuilder hou = reverse(str.substring(index));
        String zong = ""+qian+hou;
        StringBuilder reverse2 = reverse(zong);
        return reverse2.toString();
    }

    public StringBuilder reverse(String str) {
        StringBuilder sb = new StringBuilder();
        for (int i = str.length()-1; i >= 0; i--) {
            sb.append(str.charAt(i));
        }
        return sb;
    }