返回相同宽度数字型字符串

 /**返回相同闊度數字型字串. 例:
       function1(“000000”) => “000001”
       function1(”0023")   => “0024”
       function1(“0009”)   => “0010”
       function1(“000099”) => “000100”
       function1(“9”) => “0” //號碼循環再用
       程式接口:
       public static String function1(String num);
    */
     public static String function1(String num){
       int length = num.length();
       int number = 0;
       //得到字符串中的数值
       for(int i=0;i<length;i++){
           if(!(num.charAt(i)=='0')){
               number = Integer.parseInt(num.substring(i));
               break;
           }
       }
       number++;
       String returnStr = number+"";
       //得到原来宽度的字符串
       if(returnStr.length()==length){
          
       }else if(returnStr.length()>length){
           returnStr = returnStr.substring(returnStr.length()-length);
       }else{
           while(returnStr.length()<length){
               returnStr = "0" + returnStr;
           }
       }
       return returnStr;
   }

                                              //---------------------------纵横软件邮件所发笔试题1