How to format a Java string with leading zero

Question

Here is the String  for example    Apple    and I would like to add zero to fill in 8 chars    000Apple    How can I do so

User · Answer

Did anyone tried this pure Java solution (without SpringUtils):

//decimal to hex string 1=> 01, 10=>0A,..
String.format("%1$2s", Integer.toString(1,16) ).replace(" ","0");
//reply to original question, string with leading zeros. 
//first generates a 10 char long string with leading spaces, and then spaces are
//replaced by a zero string. 
String.format("%1$10s", "mystring" ).replace(" ","0");

Unfortunately this solution works only if you do not have blank spaces in a string.

User · Answer

String input    Apple   StringBuffer buf   new StringBuffer input    while  buf length    lt  8      buf insert 0   0       String output   buf toString

User · Answer

You can use the String format method as used in another answer to generate a string of 0 s   String format   0  length  d  0    This can be applied to your problem by dynamically adjusting the number of leading 0 s in a format string   public String leadingZeros String s  int length         if  s length    gt   length  return s       else return String format   0     length-s length       d s   0  s       It s still a messy solution  but has the advantage that you can specify the total length of the resulting string using an integer argument

User · Answer

In case you have to do it without the help of a library     00000000     Apple   substring  Apple  length       Works  as long as your String isn t longer than 8 chars

User · Answer

Here is the simple API-less  readable script  version I use for pre-padding a string   Simple  Readable  and Adjustable    while str length    lt  desired length    str    0  str

User · Answer

This is what he was really asking for I believe   String format   0    8 -  Apple  length      d s  0   Apple       output   000Apple

User · Answer

You can use  String format  quot  08d quot    quot Apple quot     It seems to be the simplest method and there is no need of any external library

User · Answer

It isn t pretty  but it works  If you have access apache commons i would suggest that use that  if  val length    lt  8      for  int i   0  i  lt  val - 8  i          val    0    val

User · Answer

public static String lpad String str  int requiredLength  char padChar        if  str length    gt  requiredLength            return str        else           return new String new char requiredLength - str length     replace   0   padChar    str

User · Answer

You may have to take care of edgecase  This is a generic method   public class Test       public static void main String   args           System out println padCharacter  0  8  hello               public static String padCharacter String c  int num  String str           for int i 0 i lt  num-str length   1 i    str   c str           return str

User · Answer

This is fast  amp  works for whatever length   public static String prefixZeros String value  int len        char   t   new char len       int l   value length        int k   len-l      for int i 0 i lt k i      t i   0         value getChars 0  l  t  k       return new String t

User · Answer

Using Guava s Strings utility class   Strings padStart  Apple   8   0

User · Answer

I ve been in a similar situation and I used this  It is quite concise and you don t have to deal with length or another library   String str   String format   8s   Apple    str   str replace      0      Simple and neat  String format returns     Apple  so after replacing space with zeros  it gives the desired result

User · Answer

public class PaddingLeft       public static void main String   args            String input    Apple           String result    00000000    input          int length   result length            result   result substring length - 8  length           System out println result

User · Answer

If you want to write the program in pure Java you can follow the below method or there are many String Utils to help you better with more advanced features   Using a simple static method you can achieve this as below   public static String addLeadingText int length  String pad  String value        String text   value      for  int x   0  x  lt  length - value length    x    text   pad   text      return text      You can use the above method addLeadingText length  padding text  your text   addLeadingText 8   0    Apple      The output would be 000Apple

User · Answer

You can use this   org apache commons lang StringUtils leftPad  Apple   8   0

User · Answer

Solution with method String  repeat  Java 11  String str    quot Apple quot   String formatted    quot 0 quot  repeat 8 - str length      str   If needed change 8 to another number or parameterize it

User · Answer

Can be faster then Chris Lercher answer when most of in String have exacly 8 char  int length   in length    return length    8   in     00000000    in  substring length     in my case on my machine 1 8 faster

User · Answer

public class LeadingZerosExample       public static void main String   args           int number   1500             String format below will add leading zeros  the  0 syntax             to the number above             The length of the formatted string will be 7 characters          String formatted   String format   07d   number           System out println  Number with leading zeros      formatted

User · Answer

Use Apache Commons StringUtils leftPad  or look at the code to make your own function

User · Answer

In Java   String zeroes  00000000   String apple  apple    String result zeroes substring apple length   zeroes length    apple    In Scala    Apple  foldLeft  00000000    ac e   gt ac tail e    You can also explore a way in Java 8 to do it using streams and reduce  similar to the way I did it with Scala   It s a bit different to all the other solutions and I particularly like it a lot

User · Answer

public static void main String   args        String stringForTest    Apple       int requiredLengthAfterPadding   8      int inputStringLengh   stringForTest length        int diff   requiredLengthAfterPadding - inputStringLengh      if  inputStringLengh  lt  requiredLengthAfterPadding                stringForTest   new String new char diff   replace   0    0    stringForTest            System out println stringForTest

User · Answer

StringUtils leftPad yourString  8   0      This is from commons-lang  See javadoc

[java] How to format a Java string with leading zero?

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