This was completed before the winter vacation. The original intention was to keep up with the teacher's progress, but later on, after really getting in touch with Lucene, I truly fell in love with it. I used Lucene 2.0 for everything. Additionally, you need to include the `je-analysis-1.4.0.jar` and `lucene-core-2.0.0.jar` packages to successfully compile. It will split the corresponding `.txt` files under drive D into many smaller `.txt` files. Hehe... interesting...
```java
package ch2.lucenedemo.preprocess;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Set;
```
The code provided appears to be a pre-processing utility written in Java using Lucene 2.0. It imports necessary classes for file handling and data structures such as `HashMap`, `LinkedList`, etc., which are likely used for managing and processing text data. The functionality described involves splitting `.txt` files located on drive D into multiple smaller `.txt` files.