The IDE offers a variety of compilation options. Using the Build menu, you can compile all files in a program or only those files that are new or have changed since the last compile.
For help with compiling a program, see:
Compiling a Program
Correcting Errors in Source Code
Stopping a Compile
Specifying a Target Directory for a Class File
Saving Compiler Messages
Disabling Compilation of a Single Source File
Deleting.class
Files