Java Program to Check Character is Uppercase or Lowercase

In Java, to check if a character is uppercase or lowercase, we can use either an if-else condition or the ternary operator. This article focuses on learning through examples, algorithms, detailed logic, and program explanations for better understanding.

Required Knowledge

• Java programming basics
• Java Operators
• Conditional Statements
• Ternary Operator

Problem Statement

We need to write a Java program to check if a given character is uppercase or lowercase. The program will take a character as input and print whether it is in uppercase or lowercase. This above action should be done in our program. Let’s look at an example,

Example 1:

Input: C
Output: Given character is in uppercase

Here, for the input C, Output is Output is “Given character is in uppercase”

Example 2:

Input: c
Output: Given character is in lowercase

Here, for the input c, Output is Output is “Given character is in lowercase”

Algorithm to check character is in Uppercase or Lowercase

• Start: Begin the program with character input ch
  • We use next() method to read and extract the first character using charAt(0).
• Check Condition:
  • If alphabets greater than or equal to ‘A’ and less than or equal to ‘Z’ , we say they are in uppercase
    • ch>=’A’ && ch<=’Z’ , alphabets are in uppercase
  • If alphabets greater than or equal to ‘a’ and less than or equal to ‘z’ , we say they are in lowercase
  • ch>=’a’ && ch<=’z’ , alphabets are in lowercase

Logic to check if an character is in Uppercase or Lowercase

There are multiple logics to check a given input character is in uppercase or lowercase in Java Programing language.

Logic 1: Using if-else

• Here, we are checking if a character (alphabet) is in uppercase or lowercase.
• If the character is greater than or equal to ‘A’ and less than or equal to ‘Z’, we say it is in uppercase.
• Otherwise, if the character is greater than or equal to ‘a’ and less than or equal to ‘z’, we say it is in lowercase.

if (ch >= 'A' && ch <= 'Z')
			System.out.println(ch + " is Uppercase");
		else if (ch >= 'a' && ch <= 'z')
			System.out.println(ch + " is Lowercase");
		else
			System.out.println(ch+ " is not an alphabet");

Logic 2: Ternary Operator

• This operator takes three operands and functions similarly to if-else statements. If the condition is true, it evaluates the first expression, if false, it evaluates the second expression.
• For alphabets:
  • If a character is between ‘A’ and ‘Z’, it is considered uppercase.
  • Otherwise, if it is between ‘a’ and ‘z’, it is considered lowercase.

String result;
		result =(ch >= 'A' && ch <= 'Z')?
			      ch + " is Uppercase":
		         (ch >= 'a' && ch <= 'z')?
			      ch + " is Lowercase":
		       ch+ " is not an alphabet";
		System.out.println(result);

Java Program to Check Character is Uppercase or Lowercase

Program 1: Using if-else

In the below program we are using if-else to check given character is uppercase or lowercase in Java.

import java.util.Scanner;

public class UppperCaseLowerCaseCheck {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		System.out.println("Enter a character");
		char ch = s.next().charAt(0);
		if (ch >= 'A' && ch <= 'Z')
			System.out.println(ch + " is Uppercase");
		else if (ch >= 'a' && ch <= 'z')
			System.out.println(ch + " is Lowercase");
		else
			System.out.println(ch+ " is not an alphabet");
		s.close();
	}
}

Output:

Enter a character
A
A is Uppercase

Java program explanation to check given character is Uppercase or Lowercase

• The program imports the Scanner class from java.util package to facilitate user input.
• Program defines a class named UppperCaseLowerCaseCheck.
• It contains the main method where the program execution starts.
• Asks the user to enter a character.
• Reads the user input character using Scanners next() method and extracts the first character using charAt(0).
• It checks if the input character falls within the range of uppercase letters (‘A’ to ‘Z’) using ASCII values.
• If the character is within this range, it prints that the character is uppercase.
• Otherwise, it checks if the character falls within the range of lowercase letters (‘a’ to ‘z’) using ASCII values.
• If the character is within this range, it prints that the character is lowercase.
• When neither condition is met, it prints that the character is not an alphabet.
• It closes the Scanner object s to release system resources.

Program 2: Using Ternary Operator

In the below program we are using Ternary Operator to check given character is in uppercase or lowercase in Java.

import java.util.Scanner;

public class UppperCaseLowerCaseCheck {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		System.out.println("Enter a character");
		char ch = s.next().charAt(0);
		String result;
		result =(ch >= 'A' && ch <= 'Z')?
			      ch + " is Uppercase":
		         (ch >= 'a' && ch <= 'z')?
			      ch + " is Lowercase":
		       ch+ " is not an alphabet";
		System.out.println(result);
		s.close();
	}
}

Output:

Enter a character
c
c is Lowercase

Java program explanation to check given character is Uppercase or Lowercase

• The program imports the Scanner class from java.util package to facilitate user input.
• Then it defines a class named UppperCaseLowerCaseCheck.
• It contains the main method where the program execution starts.
• Asks the user to enter a character.
• Reads the user input character using Scanner‘s next() method and extracts the first character using charAt(0).
• It uses nested ternary operators to determine whether the input character is uppercase, lowercase, or not an alphabet.
• If the character is within the range of uppercase letters (‘A’ to ‘Z’) using ASCII values, it assigns a message indicating that the character is uppercase.
• Otherwise, if the character is within the range of lowercase letters (‘a’ to ‘z’) using ASCII values, it assigns a message indicating that the character is lowercase.
• If neither condition is met, it assigns a message indicating that the character is not an alphabet.
• It prints the message indicating the result obtained from the ternary operator evaluation.
• Program closes the Scanner object s to release system resources.

Conclusion

In this article, we explored how to check if a character is in uppercase or lowercase using using if-else and the ternary operator. We understood the logic and proceed to implement the program.

For more related topics in Java, you might find these articles helpful:

• Understanding the concepts of Conditional statements in Java
• Top 10 Java Programming tips
• Concepts of Operators in Python

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Happy Java Programming!