• Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

How to keep leading zeros when doing a parseInt

 
Rita Chakras
Greenhorn
Posts: 10
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi,

I have a string which is a combination of a alpha prefix and a number suffix. I extract the prefix and get the number suffix of the string. Then, I do a Integer.parseInt on the suffix to get the value as an integer so that I can increment it. This works ok in general, but not when the suffix has leading zeros. In this case, I need to retain the leading zeros. So, for example, if the suffix is 001, when I parseInt it the integer value become 1 and then when I increment it, it becomes 2. I need it to be 001, 002.

Is there a way to do this?

Thanks in advance.
 
Paul Clapham
Sheriff
Posts: 21322
32
Eclipse IDE Firefox Browser MySQL Database
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
After you increment it, convert it back to a String with those leading zeroes.
 
Rita Chakras
Greenhorn
Posts: 10
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Problem is I'm not ever sure when the suffix has leading zeros. It depends on what value is being sent in. Also, the suffix may have 1 zeros to n number of zeros, but I don't know that. So I could have:
01, 02, 03 or I could have 08, 09, 10.
 
Paul Clapham
Sheriff
Posts: 21322
32
Eclipse IDE Firefox Browser MySQL Database
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I think you mean you want the resulting String to be N characters, and you want to add leading zeroes until it reaches N characters, right? And you do know what N is, don't you?
 
Rita Chakras
Greenhorn
Posts: 10
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Yes, I do know what N is (length of String), but I don't know if the N contains leading zeros or not, and if it does how many leading zeros. So if I increment, I don't know how many zeros I should add or when I should stop adding zeros.

I suppose I could parse through the string to figure out how many zeros it has and stop when it exceeds the length of N?
 
fred rosenberger
lowercase baba
Bartender
Posts: 12186
34
Chrome Java Linux
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
if you know the length of the original string, the length of the prefix, and the length of the incremented-then-converted-to-a-string integer part, you know how many zeros to add:

input string: prefix0000123
total length:13
prefix length: 6
length of string_after_increment (124): 3

13 - 6 - 3 = 4
 
Rob Spoor
Sheriff
Pie
Posts: 20610
63
Chrome Eclipse IDE Java Windows
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
If you use java.lang.DecimalFormat or String.format, you can specify the total number of digits. Whatever digits are not filled by the number itself are filled with zeros instead.
 
Norm Radder
Bartender
Posts: 1237
14
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
An easy way to pad with leading 0's
Compute ix to get the number of leading 0's you want

String padded = ("0000000000000"+old).substring(ix); // get rightmost chars
 
Campbell Ritchie
Sheriff
Pie
Posts: 49813
69
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Apart from the fact that String.format won't work on beginners':

int i = . . .;
String numberText = String.format("%010d", i);
 
Rita Chakras
Greenhorn
Posts: 10
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks so much for all your help. Fred's solution works well.
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic