he Normalizer class (from java.text in Java 5 and later java.text.Normalizer or java.text.Normalizer.Form) is used to transform Unicode text into a normalized form. This is crucial when comparing, storing, or searching strings that may be visually identical but have different internal Unicode representations (e.g., accented characters).
Key Features:
- Ensures consistent Unicode representation
- Supports multiple normalization forms (NFC, NFD, NFKC, NFKD)
- Makes string comparison and storage reliable across languages and inputs
Commonly Used Methods
Normalization Forms(Normalization.Form)
Simple Program
import java.text.Normalizer;
public class SimpleNormalizerExample {
public static void main(String[] args) {
String accented = "é"; // U+00E9
String decomposed = "e\u0301"; // U+0065 + U+0301
System.out.println("Are the strings equal (==)? " + (accented.equals(decomposed)));
String normalized = Normalizer.normalize(decomposed, Normalizer.Form.NFC);
System.out.println("Are they equal after normalization? " + accented.equals(normalized));
}
}
/*
Are the strings equal (==)? false
Are they equal after normalization? true
*/Problem Statement
Paani and Mahesh are building a search engine for international names. Users might input names using keyboards that decompose characters (e + ´ instead of é). To ensure all names match correctly, the system uses Normalizer to unify representations before storing and searching.
import java.text.Normalizer;
import java.util.*;
public class NameSearchEngine {
private static final List<String> database = Arrays.asList(
Normalizer.normalize("José", Normalizer.Form.NFC),
Normalizer.normalize("Renée", Normalizer.Form.NFC),
Normalizer.normalize("Björk", Normalizer.Form.NFC)
);
public static void main(String[] args) {
List<String> userInputs = Arrays.asList(
"Jose\u0301", // decomposed form of José
"Rene\u0301e", // decomposed form of Renée
"Bj\u00f6rk" // composed Björk
);
for (String input : userInputs) {
String normalizedInput = Normalizer.normalize(input, Normalizer.Form.NFC);
System.out.println("\nSearching for: " + input);
boolean found = false;
for (String name : database) {
if (name.equals(normalizedInput)) {
System.out.println("Match found: " + name);
found = true;
break;
}
}
if (!found) {
System.out.println("No match found.");
}
}
}
}
/*
Searching for: José
Match found: José
Searching for: Renée
Match found: Renée
Searching for: Björk
Match found: Björk
*/The Normalizer class is essential for text normalization, especially in globalized applications:
- Comparing strings from different sources (e.g., user input vs. DB)
- Storing names, text, or identifiers that involve accents or diacritics
- Building search engines, authentication systems, or data deduplication tools