10.4 Java

Automake provides some minimal support for Java compilation with the JAVA primary.

Any .java files listed in a _JAVA variable will be compiled with JAVAC at build time. By default, .java files are not included in the distribution, you should use the dist_ prefix to distribute them.

Here is a typical setup for distributing .java files and installing the .class files resulting from their compilation.

     javadir = $(datadir)/java
     dist_java_JAVA = a.java b.java ...

Currently Automake enforces the restriction that only one _JAVA primary can be used in a given Makefile.am. The reason for this restriction is that, in general, it isn't possible to know which .class files were generated from which .java files, so it would be impossible to know which files to install where. For instance, a .java file can define multiple classes; the resulting .class file names cannot be predicted without parsing the .java file.

There are a few variables that are used when compiling Java sources:

JAVAC

The name of the Java compiler. This defaults to ‘javac’.

JAVACFLAGS

The flags to pass to the compiler. This is considered to be a user variable (see User Variables).

AM_JAVACFLAGS

More flags to pass to the Java compiler. This, and not JAVACFLAGS, should be used when it is necessary to put Java compiler flags into Makefile.am.

JAVAROOT

The value of this variable is passed to the -d option to javac. It defaults to ‘$(top_builddir)’.

CLASSPATH_ENV

This variable is an sh expression that is used to set the CLASSPATH environment variable on the javac command line. (In the future we will probably handle class path setting differently.)