Find the Maximum Occurring Character in a given String?

package com.javacodepoint.string;

import java.util.HashMap;
import java.util.Map;

public class MaxOccurringCharacter {
	
	public static char findMaxOccurringChar(String input) {
		if (input == null || input.isEmpty()) {
			throw new IllegalArgumentException("Input string is null or empty.");
		}

		// Create a HashMap to store character frequencies
		Map<Character, Integer> charFrequencyMap = new HashMap<>();

		// Convert the input string to lowercase to make it case-insensitive
		input = input.toLowerCase();

		// Iterate through the string and count the occurrences of each character
		for (char c : input.toCharArray()) {
			// Ignore non-alphabetic characters, you can modify this condition based on your
			// requirements
			if (Character.isAlphabetic(c)) {
				charFrequencyMap.put(c, charFrequencyMap.getOrDefault(c, 0) + 1);
			}
		}

		// Find the maximum occurring character and its frequency
		char maxChar = '\0'; // Initialize maxChar to a null character
		int maxFrequency = 0;

		for (Map.Entry<Character, Integer> entry : charFrequencyMap.entrySet()) {
			int frequency = entry.getValue();
			if (frequency > maxFrequency) {
				maxFrequency = frequency;
				maxChar = entry.getKey();
			}
		}

		return maxChar;
	}

	public static void main(String[] args) {
		String inputString = "Javacodepoint";
		char maxChar = findMaxOccurringChar(inputString);

		System.out.println("Maximum occurring character: " + maxChar);
	}
}

package com.javacodepoint.string;

/*
 * Find maximum occurring character using Array
 */
public class FindMaximumOccurringChar2 {

	// method to find maximum occurring character
	static char findMaxOccurringChar(String str) {

		// count array to hold the character count
		int count[] = new int[26];

		// count the character without checking case
		str = str.toLowerCase();

		// to store maximum occurring char ASCII no
		char maxOccuringChar = 0;

		// to store max count
		int maxCount = 0;

		// iterate the string
		for (int i = 0; i < str.length(); i++) {

			// pick a character and convert in ASCII no
			int ch = (int) str.charAt(i);

			// 97 is the ascii value for 'a'
			count[ch - 97] = count[ch - 97] + 1;

			// update the max count
			if (maxCount < count[ch - 97]) {
				maxOccuringChar = (char) ch;
				maxCount = count[ch - 97];
			}
		}

		return maxOccuringChar;
	}

	// main method to test
	public static void main(String[] args) {
		System.out.println("Find Maximum Occurring Character Example");
		System.out.println("Maximum Occurring Character in \"Java\" => " + findMaxOccurringChar("Java"));
		System.out.println("Maximum Occurring Character in \"Programming\" => " + findMaxOccurringChar("Programming"));
		System.out.println("Maximum Occurring Character in \"Example\" => " + findMaxOccurringChar("Example"));
	}

}