Convert String to a String having a date format

Question

I want to write a java method that takes a string in input and outputs another string following this rule:

input        output
"123456"     "12:34:56"
"23456"      "02:34:56"
"3456"       "00:34:56"
"456"        "00:04:56"
"6"          "00:00:06"

Any help would be appreciated. Thanks.

There are two simple steps: 1) Add 0 at the beginning to have a string with a length equal to 6 2) Add ':' symbols inside the string — Sergey Malyutin, Oct 15 '14 at 15:05
write down an algorithm for the problem. First figure out what exactly needs to happen to a size 1 string to reach the desired output, then determine the steps to achieve the output with your largest string. What are the steps involved? Write them out on paper and pencil. Then list the steps in order. You have your algorithm. Convert to java. — scrappedcola, Oct 15 '14 at 15:08
possible duplicate of [Convert Java string to Time, NOT Date](http://stackoverflow.com/questions/18604408/convert-java-string-to-time-not-date) — Basil Bourque, Oct 15 '14 at 16:55

Yogendra Singh · Answer 1 · 2014-10-15T16:00:43.750

I would advice to use DateFormat as below. This will take care of all the burdens of conversion.

    DateFormat formatFrom = new SimpleDateFormat("HHmmss");
    DateFormat formatTo = new SimpleDateFormat("HH:mm:ss");
    String origTimeString = "456";
    String newDateString = null;
    try {
        String formattedString = 
                        String.format("%06d", Integer.parseInt(origTimeString));
        Date date = formatFrom.parse(formattedString);
        newDateString = formatTo.format(date);
    } catch (ParseException e) {
        e.printStackTrace();
    }
    System.out.println("Updated string : " + newDateString);

score 0 · Answer 2 · answered Oct 15 '14 at 17:04

Copy this method and use it.

1) If string length is more than 6, it's going to return "ERROR".

2) First fixes the String with '0'

3) Second fixes the String with ':'

4) StringBuilder is used for concat. Avoid using '+' operator for concat.

5) Method 'getDate' is static because of 'main' method is static, too.

public static String getDate(String variable){

    StringBuilder aux= new StringBuilder();
    StringBuilder string= new StringBuilder();
    int length = variable.length();


    if(length>6 || length<=0){
        return "ERROR";
    }else{

        //first to fill blanks with 0
        for(int i=0;i<6-length;i++){
            aux.append("0");
        }
        variable = aux.append(variable).toString();


        //second to put :
        for(int i=0;i<6;i++){

           if(i%2==0 && i!=0){  
               string.append(":");
           }
           string.append(variable.charAt(i));
        }
        return string.toString();
    }
}

public static void main(String[] args) {
    System.out.print(getDate("464"));
}

Convert String to a String having a date format

2 Answers2