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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:

Example

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} .

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