The JCompiler plugin allows for compiling java source files IN-PROCESS. It does not start a new javac process and is therefore much faster than compiling in an external process. It will also include the directory where the source file resides in the CLASSPATH during compilation. It can compile a single file or the whole current package. It will also optionally save the current buffer or all open buffers before beginning compilation.
Error messages are displayed in the Console. Therefore, you must install the Console plugin. Optionally, the errors may be passed to the ErrorList plugin, allowing highlighting and one-click navigation to error lines in the source code.