Question: How do i delete all the tables in the schema on Apache Derby DB using JDBC?

Answer: 
For actual code that does this, check [CleanDatabaseTestSetup.java](http://svn.apache.org/viewvc/db/derby/code/trunk/java/org.apache.derby.tests/org/apache/derbyTesting/junit/CleanDatabaseTestSetup.java?view=markup) in the Derby test suite section of the Derby distribution.
Download Squirrel SQL from <http://squirrel-sql.sourceforge.net/>

Connect to the database.

Expand the TABLE node.

Select the tables that you want to drop.

Right click and select -> Scripts -> Drop table scripts

Run the generated queries

You can even select delete records to empty the selected tables.