Java How To - Character Frequency in a String

How To Count Character Frequency in a String

Use a HashMap to count how many times each character appears:

import java.util.HashMap;

public class Main {
  public static void main(String[] args) {
    String text = "banana";
    HashMap<Character, Integer> freq = new HashMap<>();

    for (char c : text.toCharArray()) {
      freq.put(c, freq.getOrDefault(c, 0) + 1);
    }

    System.out.println(freq);
    // Output: {a=3, b=1, n=2}
  }
}

Explanation: We loop through each character in the string and use a HashMap to keep track of counts.
- freq.getOrDefault(c, 0) means "get the current count of this character, or 0 if it hasn't been seen yet."
- We then add 1 and put the new value back in the map.
For the string "banana", the result is {a=3, b=1, n=2}.