Simple Search Engine

A small console-based search engine written in Java.
It indexes a fixed set of documents and lets you search them using the following:

• Keywords
• Exact phrases ("search engine")
• Boolean operators (AND, OR, NOT)
• Optional sorting by relevance and then by date

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Features

• Keyword search (case-insensitive)
• Advanced search:
  • "exact phrase"
  • AND, OR, NOT
• Ranking:
  • Simple relevance score based on term and phrase matches
• Optional date sorting (newest first on ties)
• Snippets:
  • Shows a short piece of text around where the query matched

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Project Structure

Package: searchengine

• Document.java
  Represents a document with:

  • id, title, content, date
  • Methods to:
    • Check if it contains a term or phrase
    • Build a short snippet around a match

• SearchResult.java
  Holds:

  • A Document
  • A score (relevance)
  • A snippet
    Implements Comparable to sort results by score (higher first).

• InvertedIndex.java

  • Maps term -> set of documents that contain that term.
  • Built from document titles + contents.
  • Used for fast lookup of documents for each keyword.

• BooleanQueryProcessor.java

  • Parses and evaluates advanced queries:
    • Terms (e.g. java, search)
    • Phrases in quotes (e.g. "search engine")
    • AND, OR, NOT
  • Returns a Set<Document> matching the query.

• SimpleSearchEngine.java

  • Owns the list of documents and the InvertedIndex.
  • Uses BooleanQueryProcessor to find matching documents.
  • Computes a simple relevance score:
    • +1 for each query term in the document
    • • bonus for phrase matches
  • Sorts results by score and optionally by date.

• SearchApp.java

  • Has the main method.
  • Creates some sample documents.
  • Builds SimpleSearchEngine.
  • Reads queries from the console and prints:
    • Title, ID, date, score
    • Snippet

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Setup

1. Create a new Java Project: SimpleSearchEngine.
2. Create package: searchengine.
3. Add the six classes above into that package, using the code provided.
4. Right-click SearchApp.java → Run As → Java Application.

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Using the Program

When it runs, type queries in the console, for example:

• java
• search engine
• "search engine"
• java AND search
• "search engine" OR python
• search AND techniques NOT python

Then answer:

• Sort by date as well? (y/n)

The program will print the list of matching documents with scores and snippets.

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Notes / Simplifications

• Matching is case-insensitive.
• Tokenization and scoring are very simple (good for learning, not production).
• Documents are hard-coded in SearchApp.createSampleDocuments(); you can replace them with your own.