Libraries

It is often the case that it isn't practical to produce a program using only the modules that come with Java.

To cope with this reality you can use code written by others as "libraries" of functionality.¹

When running a Java program from source you can provide the libraries using --module-path <path to library jar> --add-modules ALL-MODULE-PATH. So if you had a library named tangerine.jar you could run something like the following command.

java \
    --module-path tangerine.jar \
    --add-modules ALL-MODULE-PATH \
    src/Main.java

You do not need the --add-modules ALL-MODULE-PATH if your code is itself inside of a named module. The requires in the module take care of telling Java what to include.

java \
    --module-path tangerine.jar \
    ex.mod/src/Main.java

If you use libraries you need to provide the same flags to javac when compiling your own code to share.

java \
    -g \
    -d output \
    --module-path tangerine.jar \
    --module-source-path "./*/src" \
    --module example.module

Now that you can package your own code into JARs you can share code with others for this purpose.

Libraries can depend on libraries which depend on other libraries in sprawling nightmare graphs. For now let us assume that the libraries you want to use are relatively self-contained and reasonable to download manually. Dependency resolution and procurement can be a topic for a later day. ↩

Modern Java

Libraries