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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, .class files are not included in the distribution.

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 which 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 Variables reserved for the user).

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