Camel case in Java

Java follows the camel-case syntax for naming the classes, interfaces, methods, and variables. If the name is combined with two words, the second word will start with uppercase letter always, such as maxMarks( ), lastName, ClassTest, removing all the whitespaces.

There are two ways of using Camel case:

Lower camel case where the first character of the first word is in lowercase. This convention is usually followed while naming the methods and variables. Example, firstName, lastName, actionEvent, printArray( ), etc.
The Upper camel case also known as the title case, where the first character of the first word is in uppercase. This convention is usually followed while naming the classes and interfaces. For example, Employee, Printable, etc.

Converting a normal string into camel case

A string can be converted into either the lower or upper camel case convention just by removing the spaces from the string.

Lower Camel Case Example:

Input: TutorAspire is the best tutorial site for programming languages.

Output: tutorAspireIsTheBestTutorialSiteForProgrammingLanguages.

Upper Camel Case Example:

Input: this is the java tutorial

Output: ThisIsTheJavaTutorial

Algorithm:

Traverse the character array character by character till it reaches the end.
The first letter of the string at index = 0 is either converted to lower case (when following lower camel case) or to upper case (when following upper camel case).
The array is checked for spaces, and the letter immediately following the space is converted to the upper case.
If the non-space character is encountered, it is copied to the resulting array.

Let’s implement the algorithm in a Java program.

A. Converting String to Lower Camel Case

LowerCamel.java

  public class LowerCamel  {      // function to convert the string into lower camel case      static String convertString( String s )      {          // to keep track of spaces          int ctr = 0 ;          // variable to hold the length of the string          int n = s.length( ) ;          // converting the string expression to character array          char ch[ ] = s.toCharArray( ) ;          // keep track of indices of ch[ ] array           int c = 0 ;          // traversing through each character of the array          for ( int i = 0; i < n; i++ )          {              // The first position of the array i.e., the first letter must be              // converted to lower case as we are following lower camel case              // in this program              if( i == 0 )              // converting to lower case using the toLowerCase( ) in-built function              ch[ i ] = Character.toLowerCase( ch[ i ] ) ;              // as we need to remove all the spaces in between, we check for empty              // spaces              if ( ch[ i ] == ‘ ‘ )              {                  // incrementing the space counter by 1                  ctr++ ;                  // converting the letter immediately after the space to upper case                  ch[ i + 1 ] = Character.toUpperCase( ch[ i + 1 ] ) ;                  // continue the loop                   continue ;              }              // if the space is not encountered simply copy the character              else                  ch[ c++ ] = ch[ i ] ;          }          // The size of new string will be reduced as the spaces have been removed          // Thus, returning the new string with new size          return String.valueOf( ch, 0, n – ctr ) ;      }      // Driver code      public static void main( String args[ ] )      {          // passing the name of a method          String str = “Max Marks()” ;          System.out.println( convertString( str ) ) ;          // passing the name of a variable          String str1 = “Last name” ;          System.out.println( convertString( str1 ) ) ;          // passing the String          String str2 = “TutorAspire is the best tutorial site for programming languages.” ;          System.out.println( convertString( str2 ) ) ;      }  }  

Output:

maxMarks()  lastName  tutorAspireIsTheBestTutorialSiteForProgrammingLanguages.

B. Converting String to Upper Camel Case

UpperCamel.java

  public class UpperCamel  {      // function to convert the string into upper camel case      static String convertString( String s )      {          // to keep track of spaces          int ctr = 0 ;          // variable to hold the length of the string          int n = s.length( ) ;          // converting the string expression to character array          char ch[ ] = s.toCharArray( ) ;         // // keep track of indices of ch[ ] array          int c = 0 ;          // traversing through each character of the array          for ( int i = 0; i < n; i++ )          {              // The first position of the array i.e., the first letter must be              // converted to the upper case. We checked this before the second              // if statement as that statement is executed only when it encounters space and,              // there is no space before the first letter of a string.              if( i == 0 )              // converting to upper case using the toUpperCase( ) in-built function              ch[ i ] = Character.toUpperCase( ch[ i ] ) ;              // as we need to remove all the spaces in between, we check for empty              // spaces              if ( ch[ i ] == ‘ ‘ )              {                  // incrementing the space counter by 1                  ctr++ ;                  // converting the letter immediately after the space to upper case                  ch[ i + 1 ] = Character.toUpperCase( ch[ i + 1] ) ;                  // continue the loop                   continue ;              }              // if the space is not encountered simply copy the character              else                  ch[ c++ ] = ch[ i ] ;          }          // new string will be reduced as the spaces have been removed          // Thus returning the new string with new size          return String.valueOf( ch, 0, n – ctr ) ;      }      // Driver code      public static void main( String args[ ] )      {          // passing the name of a method          String str = “class test” ;          System.out.println( convertString( str ) ) ;          // passing the name of a variable          String str1 = “employee” ;          System.out.println( convertString( str1 ) ) ;           // passing the String          String str2 = “this is the java tutorial” ;          System.out.println(convertString( str2 ) ) ;      }  }  

Output:

ClassTest  Employee  ThisIsTheJavaTutorial

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