In this tutorial, we will see “How to find the first non-repeated character in a string using Java 8?”find first non repeated character in a string using Java 8
Java 8 – How to find the First Non-Repeated Character in a String? Click To Tweet
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | /** * Find the First Non-Repeated Character in a String using Java 8 * @author Deepak Verma * */ import java.util.Map; import java.util.Optional; import java.util.function.Function; import java.util.stream.Collectors; public class Find_First_Non_Repeated_Character_in_a_String_using_Java8 { public static void main(String[] args) { System.out.println("First Non-Repeated Character in the String: 'AMAZING' is: "+firstNonRepeatedCharacter("AMAZING")); } public static Optional<Character> firstNonRepeatedCharacter(String inputString) { Map<Character, Long> characterCount = inputString.chars() .mapToObj(c -> (char) c) .collect(Collectors.groupingBy(Function.identity(), Collectors.counting())); return inputString.chars() .mapToObj(c -> (char) c) .filter(c -> characterCount.get(c) == 1) .findFirst(); } } |
Output:
1 | First Non-Repeated Character in the String: 'AMAZING' is: Optional[M] |
find first non repeated character in a string using Java 8
In the above example, The firstNonRepeatedCharacter method takes a String input which is supplied through the main method and returns an Optional<Character> which contains the first non-repeated character in the supplied string, or an empty Optional if there are no non-repeated characters present there. It uses stream API and collects the frequency of each character in the input string into a Map of Character to Long. The filtered stream of characters is later used to find the first character whose frequency is 1.
Java 8 – How to find the First Non-Repeated Character in a String? Click To Tweet
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