I can provide you with an example of a basic search engine implementation in Java. Please note that this is a simplified version and doesn't cover all aspects of a production-level search engine. Here's the code:
```java
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class SearchEngine {
private Map<String, List<String>> invertedIndex;
public SearchEngine() {
invertedIndex = new HashMap<>();
}
public void indexDocument(String documentId, String documentContent) {
String[] words = documentContent.toLowerCase().split("\\s+");
for (String word : words) {
if (!invertedIndex.containsKey(word)) {
invertedIndex.put(word, new ArrayList<>());
}
invertedIndex.get(word).add(documentId);
}
}
public List<String> search(String query) {
String[] words = query.toLowerCase().split("\\s+");
List<String> result = new ArrayList<>();
if (words.length > 0 && invertedIndex.containsKey(words[0])) {
result.addAll(invertedIndex.get(words[0]));
}
for (int i = 1; i < words.length; i++) {
String word = words[i];
if (invertedIndex.containsKey(word)) {
result.retainAll(invertedIndex.get(word));
} else {
return new ArrayList<>();
}
}
return result;
}
public static void main(String[] args) {
SearchEngine searchEngine = new SearchEngine();
// Indexing documents
searchEngine.indexDocument("document1", "This is the first document");
searchEngine.indexDocument("document2", "This is the second document");
searchEngine.indexDocument("document3", "This is the third document");
// Searching for documents
List<String> searchResult = searchEngine.search("first document");
System.out.println("Search Result:");
for (String document : searchResult) {
System.out.println(document);
}
}
}
```
This example implements a basic search engine using an inverted index data structure. The `indexDocument` method takes a document ID and content, tokenizes the content into individual words, and updates the inverted index accordingly. The `search` method takes a query, tokenizes it, and retrieves the relevant document IDs from the inverted index. The documents are then returned as search results.
In the provided example, three documents are indexed, and a search is performed for the query "first document". The search results are then printed to the console.
Please note that this is just a simple demonstration, and real-world search engines involve more complex algorithms and data structures to handle large amounts of data efficiently.
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