字符串左移位

 
/* 
 * 字符串左移,如abcdefghi左移4位后为efghiabcd 
 */  
public class ShiftLeft {  
    static String reverStr(String s){  
        int low = 0;  
        int high = s.length()-1;  
        char[] temp = new char[s.length()];  
        while(low <= high){  
            temp[low] = s.charAt(high);  
            temp[high] = s.charAt(low);  
            low++;  
            high--;  
        }  
        return String.valueOf(temp);  
    }  
    /** 
     *  
     * @param s 要移位的字符串 
     * @param digits  向左移动的位数 
     */  
    static String shift(String s,int digits){  
        if(digits==0){  
            return s;  
        }else if(digits>





0){  
            digits = digits % s.length();  
            String left = reverStr(s.substring(0, digits));  
            String right = reverStr(s.substring(digits));  
            String result = reverStr(left+right);  
            return result;  
        }else{                              //此时变为向右移digits位,即向左移动s.length() - digits位  
            digits = -digits;  
            digits = digits % s.length();  
            return shift(s,s.length()-digits);  
        }  
    }  
    public static void main(String[] args) {  
        String s = "abcdefghi";  
        System.out.println(shift(s,-3));  
    }  
      
}