07_patch_module_option

--patch-module example

Developers that checkout java.util.concurrent classes from Doug Lea's CVS will be used to compiling the source files and deploying those classes with -Xbootclasspath/p. -Xbootclasspath/p has been removed from Java, and its module replacement is the option --patch-module to override classes in a module. It can also be used to augment the contents of module. The --patch-module option is also supported by javac to compile code "as if" part of the module.

Perform the below commands to see the contents of the respective sources contained in the src folder:

• module java.base in mypatches folder

  $ tree mypatches
  

• module com.greetings in mods folder

  $ tree mods
  

• module java.base in src folder

  $ cat src/java.base/java/util/concurrent/ConcurrentHashMap.java
  

• module com.greetings in src folder

  $ cat src/com.greetings/com/greetings/Main.java
  

Note: in case one of the below .sh script fails due to the tree command, please take a look at Download and install the tree and wget command section in the README.md file and apply the appropriate solution.

Both the modules are compiled from the sources into the folders mypatch and mods respectively with the following command:

$ ./compile.sh

And we run the example twice (with and without the patched code) with the following command:

$ ./run.sh

Check the contents of both these script files (use the cat command or a text editor) to see what they are doing and why - interesting instructions and information in there.

See ../01_Greetings/README.md to learn more about package and module naming conventions and how to avoid confusions between them.