Java program to check if a character is a letter

Comprehensive Java Examples

In this program, you will learn to check if a given character is a letter. This is done using if...else statements or the ternary operator in Java.

Example1: Java program to check a letter using if...else statements

public class Alphabet {
　　　　public static void main(String[] args) {
　　　　　　　　char c = '';*';
　　　　　　　　if((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
　　　　　　　　　　　　System.out.println(c　+　" is a letter.");
　　　　　　　　else
　　　　　　　　　　　　System.out.println(c　+　" is not a letter.");
　　　　}
}

Output Result

*　Is not a letter.

In Java, a char variable stores the ASCII value of a character (0 to127between the numbers) rather than the characters themselves.

The ASCII values of lowercase letters start from97to122. The ASCII values of uppercase letters start from65to90. That is, the letter a is stored as97, the letter z is stored as122. Similarly, the letter A is stored as65, the letter Z is stored as90.

Now, when we compare the variable c between 'a' and 'z' and between 'A' and 'Z', we store the letter97to122,65to9The ASCII value of 0 is compared

Since*The ASCII value does not fall between the ASCII values of letters. Therefore, the program outputs * Is not a letter.

You can also solve the problem using the ternary operator in Java.

Example2: Java program to check a letter using the ternary operator

public class Alphabet {
　　　　public static void main(String[] args) {
　　　　　　　　char c = 'A';
　　　　　　　　
　　　　　　　　String output = (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
　　　　　　　　　　　　　　　　? c　+　"Is a letter."
　　　　　　　　　　　　　　　　: c　+　" is not a letter. ";
　　　　　　　　
　　　　　　　　System.out.println(output);
　　　　}
}

Output Result

A is a letter.

In the above program, the if-else statement is replaced by the ternary operator (? :).

Example3: Java program uses isAlphabetic() method to check letters

class Main {
　　public static void main(String[] args) {
　　　　//Declare a variable
　　　　char c = 'a';
　　　　//Check if c is a letter
　　　　if (Character.isAlphabetic(c)) {
　　　　　　System.out.println(c　+　" is a letter.");
　　　　}
　　　　else {
　　　　　　System.out.println(c　+　" is not a letter.");
　　　　}
　　}
}

Output Result

a is a letter.

In the above example, please note the following expression:

Character.isAlphabetic(c)

Here, we use the isAlphabetic() method of the Character class. If the specified variable is a letter, it returns true. Therefore, the code in the if block is executed

Comprehensive Java Examples