How can I pad an integer with zeros on the left

Question

How do you left pad an int with zeros when converting to a String in java   I m basically looking to pad out integers up to 9999 with leading zeros  e g  1   0001

User · Answer

int x   1  System out format   05d  x     if you want to print the formatted text directly onto the screen

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Here is another way to pad an integer with zeros on the left  You can increase the number of zeros as per your convenience  Have added a check to return the same value as is in case of negative number or a value greater than or equals to zeros configured  You can further modify as per your requirement              author Dinesh Lomte        public class AddLeadingZerosToNum                                param args             public static void main String   args                     System out println getLeadingZerosToNum 0            System out println getLeadingZerosToNum 7            System out println getLeadingZerosToNum 13            System out println getLeadingZerosToNum 713            System out println getLeadingZerosToNum 7013            System out println getLeadingZerosToNum 9999                                  param num         return             private static String getLeadingZerosToNum int num               Initializing the string of zeros with required size         String zeros   new String  quot 0000 quot               Validating if num value is less then zero or if the length of number             is greater then zeros configured to return the num value as is         if  num  lt  0    String valueOf num  length    gt   zeros length                  return String valueOf num                        Returning zeros in case if value is zero          if  num    0                return zeros                    return new StringBuilder zeros substring 0  zeros length   -                  String valueOf num  length     append                          String valueOf num   toString             Input 0 7 13 713 7013 9999 Output 0000 0007 0013 7013 9999

User · Answer

Use java lang String format String Object     like this   String format   05d   yournumber     for zero-padding with a length of 5  For hexadecimal output replace the d with an x as in   05x    The full formatting options are documented as part of java util Formatter

User · Answer

Try this one  import java text DecimalFormat    DecimalFormat df   new DecimalFormat  quot 0000 quot     String c   df format 9        Output  0009  String a   df format 99       Output  0099  String b   df format 999      Output  0999

User · Answer

public static String zeroPad long number  int width       long wrapAt    long Math pow 10  width      return String valueOf number   wrapAt   wrapAt  substring 1       The only problem with this approach is that it makes you put on your thinking hat to figure out how it works

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Try this one  import java text DecimalFormat    DecimalFormat df   new DecimalFormat  quot 0000 quot     String c   df format 9        Output  0009  String a   df format 99       Output  0099  String b   df format 999      Output  0999

User · Answer

If you for any reason use pre 1 5 Java then may try with Apache Commons Lang method  org apache commons lang StringUtils leftPad String str  int size   0

User · Answer

Here is how you can format your string without using DecimalFormat   String format   02d   9      09   String format   03d   19      019   String format   04d   119      0119

User · Answer

Use java lang String format String Object     like this   String format   05d   yournumber     for zero-padding with a length of 5  For hexadecimal output replace the d with an x as in   05x    The full formatting options are documented as part of java util Formatter

User · Answer

No packages needed   String paddedString   i  lt  100   i  lt  10    00    i    0    i        i    This will pad the string to three characters  and it is easy to add a part more for four or five  I know this is not the perfect solution in any way  especially if you want a large padded string   but I like it

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Check my code that will work for integer and String   Assume our first number is 2  And we want to add zeros to that so the the length of final string will be 4  For that you can use following code      int number 2      int requiredLengthAfterPadding 4      String resultString Integer toString number       int inputStringLengh resultString length        int diff requiredLengthAfterPadding-inputStringLengh      if inputStringLengh lt requiredLengthAfterPadding                resultString new String new char diff   replace   0    0   number                    System out println resultString

User · Answer

int x   1  System out format   05d  x     if you want to print the formatted text directly onto the screen

User · Answer

Found this example    Will test     import java text DecimalFormat  class TestingAndQualityAssuranceDepartment       public static void main String    args                int x 1          DecimalFormat df   new DecimalFormat  00            System out println df format x              Tested this and   String format   05d  number     Both work  for  my purposes I think String Format is better and more succinct

User · Answer

If you for any reason use pre 1 5 Java then may try with Apache Commons Lang method  org apache commons lang StringUtils leftPad String str  int size   0

User · Answer

You can use Google Guava   Maven    lt dependency gt        lt artifactId gt guava lt  artifactId gt        lt groupId gt com google guava lt  groupId gt        lt version gt 14 0 1 lt  version gt   lt  dependency gt    Sample code   String paddedString1   Strings padStart  7   3   0       007  String paddedString2   Strings padStart  2020   3   0       2020    Note   Guava is very useful library  it also provides lots of features which related to Collections  Caches  Functional idioms  Concurrency  Strings  Primitives  Ranges  IO  Hashing  EventBus  etc  Ref  GuavaExplained

User · Answer

Found this example    Will test     import java text DecimalFormat  class TestingAndQualityAssuranceDepartment       public static void main String    args                int x 1          DecimalFormat df   new DecimalFormat  00            System out println df format x              Tested this and   String format   05d  number     Both work  for  my purposes I think String Format is better and more succinct

User · Answer

public static String zeroPad long number  int width       long wrapAt    long Math pow 10  width      return String valueOf number   wrapAt   wrapAt  substring 1       The only problem with this approach is that it makes you put on your thinking hat to figure out how it works

User · Answer

Check my code that will work for integer and String   Assume our first number is 2  And we want to add zeros to that so the the length of final string will be 4  For that you can use following code      int number 2      int requiredLengthAfterPadding 4      String resultString Integer toString number       int inputStringLengh resultString length        int diff requiredLengthAfterPadding-inputStringLengh      if inputStringLengh lt requiredLengthAfterPadding                resultString new String new char diff   replace   0    0   number                    System out println resultString

User · Answer

Let s say you want to print 11 as 011  You could use a formatter    03d      You can use this formatter like this   int a   11  String with3digits   String format   03d   a   System out println with3digits     Alternatively  some java methods directly support these formatters   System out printf   03d   a

User · Answer

Use java lang String format String Object     like this   String format   05d   yournumber     for zero-padding with a length of 5  For hexadecimal output replace the d with an x as in   05x    The full formatting options are documented as part of java util Formatter

User · Answer

If you for any reason use pre 1 5 Java then may try with Apache Commons Lang method  org apache commons lang StringUtils leftPad String str  int size   0

User · Answer

Found this example    Will test     import java text DecimalFormat  class TestingAndQualityAssuranceDepartment       public static void main String    args                int x 1          DecimalFormat df   new DecimalFormat  00            System out println df format x              Tested this and   String format   05d  number     Both work  for  my purposes I think String Format is better and more succinct

User · Answer

Here is another way to pad an integer with zeros on the left  You can increase the number of zeros as per your convenience  Have added a check to return the same value as is in case of negative number or a value greater than or equals to zeros configured  You can further modify as per your requirement              author Dinesh Lomte        public class AddLeadingZerosToNum                                param args             public static void main String   args                     System out println getLeadingZerosToNum 0            System out println getLeadingZerosToNum 7            System out println getLeadingZerosToNum 13            System out println getLeadingZerosToNum 713            System out println getLeadingZerosToNum 7013            System out println getLeadingZerosToNum 9999                                  param num         return             private static String getLeadingZerosToNum int num               Initializing the string of zeros with required size         String zeros   new String  quot 0000 quot               Validating if num value is less then zero or if the length of number             is greater then zeros configured to return the num value as is         if  num  lt  0    String valueOf num  length    gt   zeros length                  return String valueOf num                        Returning zeros in case if value is zero          if  num    0                return zeros                    return new StringBuilder zeros substring 0  zeros length   -                  String valueOf num  length     append                          String valueOf num   toString             Input 0 7 13 713 7013 9999 Output 0000 0007 0013 7013 9999

User · Answer

Found this example    Will test     import java text DecimalFormat  class TestingAndQualityAssuranceDepartment       public static void main String    args                int x 1          DecimalFormat df   new DecimalFormat  00            System out println df format x              Tested this and   String format   05d  number     Both work  for  my purposes I think String Format is better and more succinct

User · Answer

You can use Google Guava   Maven    lt dependency gt        lt artifactId gt guava lt  artifactId gt        lt groupId gt com google guava lt  groupId gt        lt version gt 14 0 1 lt  version gt   lt  dependency gt    Sample code   String paddedString1   Strings padStart  7   3   0       007  String paddedString2   Strings padStart  2020   3   0       2020    Note   Guava is very useful library  it also provides lots of features which related to Collections  Caches  Functional idioms  Concurrency  Strings  Primitives  Ranges  IO  Hashing  EventBus  etc  Ref  GuavaExplained

User · Answer

Use the class DecimalFormat  like so   NumberFormat formatter   new DecimalFormat  0000      i use 4 Zero but you can also another number System out println  OUTPUT     formatter format 811       OUTPUT   0000811

User · Answer

You need to use a Formatter  following code uses NumberFormat      int inputNo   1      NumberFormat nf   NumberFormat getInstance        nf setMaximumIntegerDigits 4       nf setMinimumIntegerDigits 4       nf setGroupingUsed false        System out println  Formatted Integer       nf format inputNo         Output  0001

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If performance is important in your case you could do it yourself with less overhead compared to the String format function           param in The integer value     param fill The number of digits to fill     return The given value left padded with the given number of digits     public static String lPadZero int in  int fill        boolean negative   false      int value  len   0       if in  gt   0           value   in        else           negative   true          value   - in          in   - in          len                if value    0           len   1        else                   for   value    0  len                  value    10                       StringBuilder sb   new StringBuilder         if negative           sb append  -               for int i   fill  i  gt  len  i--           sb append  0               sb append in        return sb toString               Performance  public static void main String   args        Random rdm      long start           Using own function     rdm   new Random 0       start   System nanoTime         for int i   10000000  i    0  i--           lPadZero rdm nextInt 20000  - 10000  4             System out println  Own function        System nanoTime   - start    1000000     ms            Using String format     rdm   new Random 0               start   System nanoTime         for int i   10000000  i    0  i--           String format   04d   rdm nextInt 20000  - 10000             System out println  String format        System nanoTime   - start    1000000     ms        Result  Own function  1697ms  String format  38134ms

User · Answer

Here is how you can format your string without using DecimalFormat   String format   02d   9      09   String format   03d   19      019   String format   04d   119      0119

User · Answer

Although many of the above approaches are good  but sometimes we need to format integers as well as floats  We can use this  particularly when we need to pad particular number of zeroes on left as well as right of decimal numbers   import java text NumberFormat    public class NumberFormatMain      public static void main String   args          int intNumber   25        float floatNumber   25 546f        NumberFormat format NumberFormat getInstance          format setMaximumIntegerDigits 6         format setMaximumFractionDigits 6         format setMinimumFractionDigits 6         format setMinimumIntegerDigits 6          System out println  Formatted Integer     format format intNumber  replace                 System out println  Formatted Float       format format floatNumber  replace

User · Answer

Use java lang String format String Object     like this   String format   05d   yournumber     for zero-padding with a length of 5  For hexadecimal output replace the d with an x as in   05x    The full formatting options are documented as part of java util Formatter

User · Answer

Although many of the above approaches are good  but sometimes we need to format integers as well as floats  We can use this  particularly when we need to pad particular number of zeroes on left as well as right of decimal numbers   import java text NumberFormat    public class NumberFormatMain      public static void main String   args          int intNumber   25        float floatNumber   25 546f        NumberFormat format NumberFormat getInstance          format setMaximumIntegerDigits 6         format setMaximumFractionDigits 6         format setMinimumFractionDigits 6         format setMinimumIntegerDigits 6          System out println  Formatted Integer     format format intNumber  replace                 System out println  Formatted Float       format format floatNumber  replace

User · Answer

No packages needed   String paddedString   i  lt  100   i  lt  10    00    i    0    i        i    This will pad the string to three characters  and it is easy to add a part more for four or five  I know this is not the perfect solution in any way  especially if you want a large padded string   but I like it

User · Answer

Use the class DecimalFormat  like so   NumberFormat formatter   new DecimalFormat  0000      i use 4 Zero but you can also another number System out println  OUTPUT     formatter format 811       OUTPUT   0000811

User · Answer

If performance is important in your case you could do it yourself with less overhead compared to the String format function           param in The integer value     param fill The number of digits to fill     return The given value left padded with the given number of digits     public static String lPadZero int in  int fill        boolean negative   false      int value  len   0       if in  gt   0           value   in        else           negative   true          value   - in          in   - in          len                if value    0           len   1        else                   for   value    0  len                  value    10                       StringBuilder sb   new StringBuilder         if negative           sb append  -               for int i   fill  i  gt  len  i--           sb append  0               sb append in        return sb toString               Performance  public static void main String   args        Random rdm      long start           Using own function     rdm   new Random 0       start   System nanoTime         for int i   10000000  i    0  i--           lPadZero rdm nextInt 20000  - 10000  4             System out println  Own function        System nanoTime   - start    1000000     ms            Using String format     rdm   new Random 0               start   System nanoTime         for int i   10000000  i    0  i--           String format   04d   rdm nextInt 20000  - 10000             System out println  String format        System nanoTime   - start    1000000     ms        Result  Own function  1697ms  String format  38134ms

User · Answer

You need to use a Formatter  following code uses NumberFormat      int inputNo   1      NumberFormat nf   NumberFormat getInstance        nf setMaximumIntegerDigits 4       nf setMinimumIntegerDigits 4       nf setGroupingUsed false        System out println  Formatted Integer       nf format inputNo         Output  0001

User · Answer

Let s say you want to print 11 as 011  You could use a formatter    03d      You can use this formatter like this   int a   11  String with3digits   String format   03d   a   System out println with3digits     Alternatively  some java methods directly support these formatters   System out printf   03d   a

User · Answer

If you for any reason use pre 1 5 Java then may try with Apache Commons Lang method  org apache commons lang StringUtils leftPad String str  int size   0

[java] How can I pad an integer with zeros on the left?

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