All the packages exported by java.base module are automatically available to all the modules.įind the diagram that shows relation between module, packages and classes. java.base module contains the packages such as java.lang, java.io,, java.util etc.
Base module is java.base which is automatically resolved by all modules. We can also export packages to only friend modules and not for all.Ī module is created with module-info.java file name and module keyword is used to specify module name. So only exported packages from a module will be available to packages of other modules. In next session we will discuss Setup Classpath/ Environment variable and Compiling, running and debugging Java programs. Java class can have instance variable such as methods, instance variable. java extension The command line contains the source version option If the file does not follow the standard naming conventions for Java source.
The source-file mode is enabled if one of the following two conditions are true: The first item on the command line followed by the JVM options is a file name with the. Once the current working directory of the command prompt window is set you can run the Java compiler by typing javac a space, the name of the code file. We can export the packages from its module to make it available to packages of other modules. One Java file can have multiple classes declared in it but only one public class which should be same as file name. The Java launcher introduced a new source-file mode to support this feature. Public methods of packages are only available for packages within the module. Now using Module, we can control the accessibility between packages for public methods of the classes.Ī Package is the set of classes and a Module is the set of packages. For a large number of source files, list the file names in a file, separated by blanks or line breaks. In a large code base, where there is large number of packages, any package can access public method of any package which was not a better accessibility control. There are two ways to pass source code file names to javac: For a small number of source files, simply list the file names on the command line. Before Java 9 module, Java programs are packages.Īs we know that in Java, a package can access only public methods of another packages. Command make is used to compile program through Makefile, since there are only one target all in the Makefile, so we do not need to mention target name because first target is got compiled automatically. In Java we have classes, packages and now modules, too. gcc is compiler name, main.c, misc.c source file names, -o is linker flag and main is binary file name. Java Module is the main feature introduced in Java 9 release. A Module is a set of packages designed for reuse. This is necessary for cases when the source file is a ¬script to be executed and the name of the source file does not follow the normal naming conventions for Java source files. java extension, the -source option must be used to force source-file mode.
Note that I said file name and not class name.
This page will walk through Java 9 Module Example. In other words, Java will look for the first