How to Add Spaces to a String in Java

How to pad a String in Java

Given a string str of some specific length, the task is to pad this string with the given character ch, inorder to make the string of length L.

Note: Padding has to be done in all three formats: Left Padding, Right Padding and Center Padding.

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Example:

Input: str = "Geeksforgeeks", ch ='-', L = 20
Output:
Left Padding: ————GeeksForGeeks
Center Padding: ——GeeksForGeeks——
Right Padding: GeeksForGeeks————

Input: str = "GfG", ch ='#', L = 5
Output:
Left Padding: ##GfG
Center Padding: #GfG#
Right Padding: GfG##

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

There are many methods to pad a String:

1. Using String format() method: This method is used to return a formatted string using the given locale, specified format string and arguments.

   Note: This method can be used to do only left and right padding.

   Approach:

   • Get the string in which padding is done.
   • Use the String.format() method to pad the string with spaces on left and right, and then replace these spaces with the given character using String.replace() method.
   • For left padding, the syntax to use the String.format() method is:

     String.format("%[L]s", str).replace(' ', ch);                  

   • For right padding, the syntax to use the String.format() method is:

     String.format("%-[L]s", str).replace(' ', ch);                  

   • If the length 'L' is less than initial length of the string, then the same string is returned unaltered.

   Below is the implementation of the above approach:

   Example:

   import java.lang.*;

   import java.io.*;

   public class GFG {

   public static String

   leftPadding(String input, char ch, int L)

   {

   String result

   = String

   .format( "%" + L + "s" , input)

   .replace( ' ' , ch);

   return result;

   }

   public static String

   rightPadding(String input, char ch, int L)

   {

   String result

   = String

   .format( "%" + (-L) + "s" , input)

   .replace( ' ' , ch);

   return result;

   }

   public static void main(String[] args)

   {

   String str = "GeeksForGeeks" ;

   char ch = '-' ;

   int L = 20 ;

   System.out.println(

   leftPadding(str, ch, L));

   System.out.println(

   rightPadding(str, ch, L));

   }

   }

   Output:

   -------GeeksForGeeks GeeksForGeeks-------                

2. Using Apache Common Lang: Apache Commons Lang package provides the StringUtils class, which contains the leftPad(), center() and rightPad() method to easily left pad, center pad and right pad a String respectively.

   Note: This module has to be installed before running of the code. Hence this code won't run on Online compilers.

   Approach:

   • Get the string in which padding is done.
   • For left padding, the syntax to use the StringUtils.leftPad() method is:

     StringUtils.leftPad(str, L, ch);                  

   • For center padding, the syntax to use the StringUtils.center() method is:

     StringUtils.center(str, L, ch);                  

   • For right padding, the syntax to use the StringUtils.rightPad() method is:

     StringUtils.rightPad(str, L, ch);                  

   • If the length 'L' is less than initial length of the string, then the same string is returned unaltered.

   Below is the implementation of the above approach:

   Example:

   import java.lang.*;

   import java.io.*;

   public class GFG {

   public static String

   leftPadding(String input, char ch, int L)

   {

   String result

   = StringUtils.leftPad(str, L, ch);

   return result;

   }

   public static String

   centerPadding(String input, char ch, int L)

   {

   String result

   = StringUtils.center(str, L, ch);

   return result;

   }

   public static String

   rightPadding(String input, char ch, int L)

   {

   String result

   = StringUtils.rightPad(str, L, ch);

   return result;

   }

   public static void main(String[] args)

   {

   String str = "GeeksForGeeks" ;

   char ch = '-' ;

   int L = 20 ;

   System.out.println(

   leftPadding(str, ch, L));

   System.out.println(

   centerPadding(str, ch, L));

   System.out.println(

   rightPadding(str, ch, L));

   }

   }

   Output:

   -------GeeksForGeeks ---GeeksForGeeks---- GeeksForGeeks-------                

How to Add Spaces to a String in Java

Source: https://www.geeksforgeeks.org/how-to-pad-a-string-in-java/

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