Java – Unique characters in String
To get the unique characters in a string in Java, you can iterate over the characters in a string using a For loop, and maintain the unique characters in a set using a HashSet.
In this tutorial, we will learn how to use a For loop and a HashSet to get the unique characters in a string in Java, with examples.
1. Get unique characters in String using HashSet in Java
Steps to get unique characters in a string using HashSet.
- Given a string in str.
- Initialize an empty HashSet uniqueChars.
- Iterate over the characters of string using a For loop.
- Add character to the set uniqueChars.
- You have all the unique characters in the given string collected into uniqueChars set. You may print these unique characters.
Now, let us write a Java program, to get the unique characters of a string "Hello World"
and print them to output.
Java Program
import java.util.HashSet; import java.util.Set; public class Main { public static void main(String[] args) { String str = "HelloWorld"; Set<Character> uniqueCharacters = new HashSet<>(); // Get unique characters in the string for(char ch: str.toCharArray()) { uniqueCharacters.add(ch); } // Print the unique characters for(char ch: uniqueCharacters) { System.out.println(ch); } } }
Output
r d e W H l o
Conclusion
In this Java String tutorial, we have seen how to get the unique characters in a string in Java using a For loop and HashSet, with examples.