Java API compatibility testing tools


The general usage of japize is as follows:

$ japize [unzip] [as <name>] apis <zipfile> | <dir> ... +|-<pkgpath> ...

At least one +<pkgpath> is required. <name> will have ".japi" and/or ".gz" appended as appropriate.

The word "apis" can be replaced by "explicitly", "byname", "packages" or "classes". These options indicate whether something of the form "a.b.C" should be treated as a class or a package. You may specify this unambiguously by using one of the forms "a.b.cpackage," or "a.b,CClass".

That's the one-paragraph overview, pretty much equivalent to what you get if you type "japize" with no arguments. In detail, the options available are as follows:


Specifying the "unzip" option indicates that japize should not gzip its output. Zipping the output is highly recommended since it saves huge amounts of space (japi files are large but extremely compressable because they contain large numbers of duplicate strings. Factor-of-ten compression seems to be typical). The only situations where you might not want to use gzip compression are when memory and CPU usage are extremely tight (zipping and unzipping both require more memory the larger the file gets, and require more CPU usage - on todays computers this is rarely an issue, though) or if your JVM does not implement GZIPOutputStream correctly (in which case you might still want to gzip the resulting file manually).

as <name>

Specifying this option tells japize to write its output to a file with the specified name. When writing to a file with the "as" option, japize insists on writing to a file name ending in .japi.gz for compressed files, or .japi for uncompressed files. If the filename you specify doesn't have the right extension, japize will add parts to it to ensure that it does.

If the "as" option is omitted, japize will write to standard output. In this case japize has no control over the filename you use, but it is strongly recommended to use a filename with the correct extension (".japi.gz" unless the "unzip" option was specified). If you use any other extension, japicompat and other tools may be unable to recognize the format.

apis | explicitly | byname | packages | classes

This option has a dual role: it indicates the boundary between japize options (unzip, as) and other arguments (files and packages), but also tells japize how to deal with ambiguously specified arguments. See "+|-<pkgpath>" below for details on the behavior of each option. If you are unsure which to specify, "apis" is a safe choice.

<zipfile> | <dir>

Any arguments after "apis" that do not start with "+" or "-" are taken to be zipfiles or directories. These should be specified exactly as you would put them in your CLASSPATH (except separated by spaces rather than colons). Anything that's a file will be assumed to be a zip (or jar) file, so you can't specify a .class file directly - if you need to do that you should specify the folder containing it and then name the class for processing.


To specify which classes are included, use +pkgpath to add pkgpaths to be scanned and -pkgpath to exclude sub-pkgpaths of these. You MUST specify at least one +pkgpath option to specify which pkgpath to include, otherwise Japize could happily scan through all the zipfiles and directories but not actually process any of the classes. Since that would be a useless thing to do, japize gives an error instead.

A "pkgpath" refers to either a package (which includes, by implication, all sub-packages of it) or a single class. A pkgpath for a package looks like "com.foo.pkg.sub," and a pkgpath for a class looks like "com.foo.pkg,Cls". The existence and placement of the comma indicates unambiguously which type of path is intended.

Most of the time, though, it's a pain to have to put in commas in names that are familiar with dots instead, and get the comma placement exactly right. For this reason, japize accepts pkgpaths containing only dots, and lets you tell it what to make of those names. The interpretation of "a.b.c" as a pkgpath depends on whether you specified apis, explicitly, byname, packages, or classes.

a.b.c is tried both as a package and a class. This will always do what you want (which is why apis is described as the safe default) but at the expense of possibly doing extra unnecessary processing trying to find the wrong thing.
pkgpaths of the form a.b.c are illegal - you must use the explicit form.
a.b.c will be processed as a package if "c" starts with a lowercase letter, or as a class if it starts with an uppercase one. This usually does what you want but fails on things like org.omg.CORBA.
a.b.c will be processed as a package. If processing for a class is needed, it must be specified explicitly.
a.b.c will be processed as a class. If processing for a package is needed, it must be specified explicitly.


As an example, Sun's JDK 1.1 includes classes in java.awt.peer and in java.text.resources that are not part of the public API, even though they are public classes; however, every other class in the java.* package hierarchy is part of the public API. The syntax to construct a useful jdk11.japi.gz would therefore be:

$ japize as jdk11 apis classes.zip +java -java.awt.peer -java.text.resources

Note that since all pkgpath arguments here are packages, you could save a small amount of processing by doing this instead:

$ japize as jdk11 packages classes.zip +java -java.awt.peer -java.text.resources

or even this:

$ japize as jdk11 explicitly classes.zip +java, -java.awt.peer, -java.text.resources,

Another example, this time doing the same thing for kaffe:

$ japize as kaffe packages $KAFFEHOME/share/kaffe/Klasses.jar
 $KAFFEHOME/share/kaffe/rmi.jar +java -java.awt.peer -java.text.resources