Unzip the distribution file you have downloaded:
Change to the Janino directory
You will find the Janino JAR files, the source code ZIP files, the text of the BSD license, and a README file.
Put "commons-compiler.jar" and "janino.jar" on your class path.
If you're using an IDE like ECLIPSE, you can optionally have "commons-compiler-src.zip" as the source attachment of "commons-compiler.jar", and "janino-src.zip" as the source attachment of "janino.jar". That'll get you tooltip JAVADOC and source level debugging into the JANINO libraries.
Use one of the features, e.g. the "expression evaluator", in your program:
Compile, run, ... be happy!
The ShippingCost class demonstrates how easy it is to use Janino as an expression evaluator.
The ExpressionDemo class implements a command line-based test environment for the expression evaluator.
The ScriptDemo class implements a command line-based test environment for the script evaluator.
The ClassBodyDemo class implements a command line-based test environment for the class body evaluator.
The DeclarationCounter class implements a command-line utility that counts class, interface, field and local variable declarations in a set of JavaTM source files.