Java.lang.Character Class in Java

Java provides a wrapper class Character in java.lang package. An object of type Character contains a single field, whose type is char.

  • Creating a Character object :
    Character ch = new Character('a');
    

    The above statement creates a Character object which contain ‘a’ of type char. There is only one constructor in Character class which expect an argument of char data type.

  • If we pass a primitive char into a method that expects an object, the compiler automatically converts the char to a Character class object. This feature is called Autoboxing and Unboxing.
  • Note : The Character class is immutable like String class i.e once it’s object is created, it cannot be changed.

Methods in Character Class :

    1. boolean isLetter(char ch) : This method is used to determine whether the specified char value(ch) is a letter or not. The method will return true if it is letter([A-Z],[a-z]), otherwise return false. In place of character, we can also pass ASCII value as an argument as char to int is implicitly typecasted in java.
      Syntax : 
      boolean isLetter(char ch)
      Parameters : 
      ch - a primitive character
      Returns :
      returns true if ch is a alphabet, otherwise return false
      
      // Java program to demonstrate isLetter() method
      public class Test
      {
          public static void main(String[] args)
          {
              System.out.println(Character.isLetter('A')); 
          	
          	System.out.println(Character.isLetter('0')); 
          	
           }
      }
      

      Output:

      true
      false
      
    2. boolean isDigit(char ch) : This method is used to determine whether the specified char value(ch) is a digit or not. Here also we can pass ASCII value as an argument.
      Syntax : 
      boolean isDigit(char ch)
      Parameters : 
      ch - a primitive character 
      Returns :
      returns true if ch is a digit, otherwise return false
      
      // Java program to demonstrate isDigit() method
      public class Test
      {
          public static void main(String[] args)
          {
              // print false as A is character
          	System.out.println(Character.isDigit('A')); 
          	
          	System.out.println(Character.isDigit('0')); 
          	
          }
      }
      

      Output:

      false
      true
      
    3. boolean isWhitespace(char ch) : It determines whether the specified char value(ch) is white space. A whitespace includes space, tab, or new line.
      Syntax : 
      boolean isWhitespace(char ch)
      Parameters : 
      ch - a primitive character 
      Returns :
      returns true if ch is a whitespace.
      otherwise return false
      
      // Java program to demonstrate isWhitespace() method
      public class Test
      {
          public static void main(String[] args)
          {
          	System.out.println(Character.isWhitespace('A')); 
          	System.out.println(Character.isWhitespace(' ')); 
          	System.out.println(Character.isWhitespace('\n')); 
          	System.out.println(Character.isWhitespace('\t')); 
          	
          	//ASCII value of tab
          	System.out.println(Character.isWhitespace(9));
          	
          	System.out.println(Character.isWhitespace('9')); 
          }
      }
      

      Output:

      false
      true
      true
      true
      true
      false
      
    4. boolean isUpperCase(char ch) : It determines whether the specified char value(ch) is uppercase or not.
      Syntax : 
      boolean isUpperCase(char ch)
      
      // Java program to demonstrate isUpperCase() method
      public class Test
      {
        public static void main(String[] args)
        {
          System.out.println(Character.isUpperCase('A'));
          System.out.println(Character.isUpperCase('a'));
          System.out.println(Character.isUpperCase(65)); 
        }
      }
      

      Output:

      true
      false
      true
      
    5. boolean isLowerCase(char ch) : It determines whether the specified char value(ch) is lowercase or not.
      Syntax : 
      boolean isLowerCase(char ch)
      
      // Java program to demonstrate isLowerCase() method
      public class Test
      {
        public static void main(String[] args)
        {
          System.out.println(Character.isLowerCase('A')); 
          System.out.println(Character.isLowerCase('a')); 
          System.out.println(Character.isLowerCase(97)); 
         }
      }
      

      Output:

      false
      true
      true
      
    6. char toUpperCase(char ch) : It returns the uppercase of the specified char value(ch). If an ASCII value is passed, then the ASCII value of it’s uppercase will be returned.
      Syntax : 
      char toUpperCase(char ch)
      Parameters : 
      ch - a primitive character 
      Returns :
      returns the uppercase form of the specified char value.
      
      // Java program to demonstrate toUpperCase() method
      public class Test
      {
         public static void main(String[] args)
         {
           System.out.println(Character.toUpperCase('a')); 
           System.out.println(Character.toUpperCase(97)); 
           System.out.println(Character.toUpperCase(48));
         }
      }
      

      Output:

      A
      65
      48
      
    7. char toLowerCase(char ch) : It returns the lowercase of the specified char value(ch).
      Syntax : 
      char toLowerCase(char ch)
      Parameters : 
      ch - a primitive character 
      Returns :
      returns the lowercase form of the specified char value.
      
      // Java program to demonstrate toLowerCase() method
      public class Test
      {
         public static void main(String[] args)
         {
           System.out.println(Character.toLowerCase('A')); 
           System.out.println(Character.toLowerCase(65)); 
           System.out.println(Character.toLowerCase(48)); 
         }
      }
      

      Output:

      a
      97
      48
      
    8. toString(char ch) : It returns a String class object representing the specified character value(ch) i.e a one-character string. Here we cannot pass ASCII value.
      Syntax : 
      String toString(char ch)
      Parameters : 
      ch - a primitive character 
      Returns :
      returns a String object.
      
      // Java program to demonstrate toString() method
      public class Test
      {
         public static void main(String[] args)
         {
          System.out.println(Character.toString('x')); 
          System.out.println(Character.toString('Y')); 
         }
      }
      

      Output:

      x
      y
      

Escape Sequences :
A character preceded by a backslash (\) is an escape sequence and has special meaning to the compiler. The following table shows the Java escape sequences:

Escape Sequence Description
\t Insert a tab in the text at this point.
\b Insert a backspace in the text at this point.
\n Insert a newline in the text at this point.
\r Insert a carriage return in the text at this point.
\f Insert a formfeed in the text at this point.
\' Insert a single quote character in the text at this point.
\" Insert a double quote character in the text at this point.
\\ Insert a backslash character in the text at this point.

When an escape sequence is encountered in a print statement, the compiler interprets it accordingly. For example, if you want to put quotes within quotes you must use the escape sequence, \", on the interior quotes. To print the sentence

She said "Hello!" to me.

you would write

System.out.println("She said \"Hello!\" to me.");

This article is contributed by Gaurav Miglani. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



My Personal Notes arrow_drop_up



Practice Tags :

Recommended Posts:



1.5 Average Difficulty : 1.5/5.0
Based on 2 vote(s)






User Actions