CelerCOM is a minimalistic Java library, which can be used to interact with external devices over COM ports, for example: USB, virtual COM. It can be used to interact with TTY and FIFO files as well. The library has no external dependencies. Native drivers are included for 32-bit and 64-bit Windows and Linux. A pure Java driver is available as a fallback for other OS and architectures.
Just add CelerCOM.jar to you classpath. The API is described in the javadoc documentation.
The TTY example shows how to read and write text commands (i.e. AT commands) through the console.