Character Frequency in Java: Explanation & Practice

Problem summary

Write a program that counts the frequency of each character in a string.

Starter code

public class Main {
    public static void main(String[] args) {
        String text = "hello"; // Test case 1
        
        // Count and print frequency of each unique char
        // Format: <char>: <count> (one per line, alphabetical order)
    }
}

Expected output and test cases

• hello frequencies

  e: 1
  h: 1
  l: 2
  o: 1

• aaabb frequencies

  a: 3
  b: 2

• Single character

  a: 1

Hints

1. Use array or HashMap for counts
2. Iterate through string once
3. Sort characters for ordered output

Related Strings exercises

• Practice Longest Word in Java
• Practice Remove All Spaces in Java
• Practice String Compression in Java

Practice all Strings exercises · Run this idea in the Java compiler