Determining Letter Characters with isLetter() Method in Java: A Comprehensive Guide

Description

A character is considered to be a letter if its general category type, provided by Character.getType(ch), is any of the following:

• UPPERCASE_LETTER
• LOWERCASE_LETTER
• TITLECASE_LETTER
• MODIFIER_LETTER
• OTHER_LETTER

Not all letters have case. Many characters are letters but are neither uppercase nor lowercase nor titlecase.

This method cannot handle supplementary characters. To support all Unicode characters, including supplementary characters, use the isLetter(int) method.

The isLetter(char ch) method of Character class is static thus it should be accessed statically which means the we would be calling this method in this format:

Non static method is usually called by just declaring method_name(argument) however in this case since the method is static, it should be called by appending the class name as suffix. We will be encountering a compilation problem if we call the java isLetter() method non statically.

The method determines whether the specified char value is a letter.

Method Syntax

boolean isLetter(char ch)

Method Argument

Data Type	Parameter	Description
char	ch	the character to be tested.

Method Returns

This method returns true if the passed character is really a character.

Compatibility

Requires Java 1.0 and up

Example

Below is a simple java example on the usage of isLetter(char ch) method of Character class.

public class MethodisLetter {

   public static void main(String args[]) {
      System.out.println(Character.isLetter('s'));
      System.out.println(Character.isLetter('2'));
   }
}

output

This will produce the following result ?

true
false
Press any key to continue . . .

Example

Below is a simple java example on the usage of isLetter(char ch) method of Character class.

import java.util.Scanner;

/*
 * This example source code demonstrates the use of
 * isLetter(char ch) method of Character class.
 */

public class CharacterIsLetterChar {

	public static void main(String[] args) {


		// Ask for user input
		System.out.print("Enter a character:");

		// use scanner to get the user input
		Scanner s = new Scanner(System.in);

		// get a single character
		char value = s.nextLine().toCharArray()[0];

		// close the scanner object
		s.close();

		// check if the user input is a letter or not
		boolean checkBool = Character.isLetter(value);
		// print result
		if(checkBool){
			System.out.println("User input \'"+value+"\' is a letter");
		}
		else{
			System.out.println("User input \'"+value+"\' is not a letter");
		}

	}

}

output

This will produce the following result ?

Enter a character:s
User input 's' is a letter
Press any key to continue . . .


Enter a character:6
User input '6' is not a letter
Press any key to continue . . .