WikiSearch.java uses the MediaWiki Action API to search Wikipedia.
The user supplies a string of keywords, and matching page titles and short snippets from each page are listed.
WikiSearch.java processes its command line arguments using the Picocli library, which I've described in more detail here. The JSON data returned by Java's HttpClient is converted to objects using Google GSON, with the mappings defined in WikiResponse.java.
WikiSearch help:
A search for "wilmslow":
A search for "imperial college" that also displays the fourth match (v 4):