Apache API in Java

1. How to implement the hashCode and equals method using Apache Commons in Java.?
2. How to write to a file line by line using Apache Commons-io API in Java ?.
3. How to clean contents of a directory using Apache commons-io API in Java ?
4. How to search for files in a directory based on extension using Apache commons-io API in Java ?
5. How to read a file contents and convert it to String using Apache commons-io API in Java ?
6. How to read a file contents line by line using Apache commons-io API in Java ?