The JDK's modularization

By now, you have a firm appreciation of Java 9's modularization. The old adage in Java, and other object-oriented programming language, is everything is a class. Now, with Java 9, everything is a module is the new adage. There are three type of modules as explained as follows:

Module type	Description
Automatic	When a JAR is placed on a new module path, modules are automatically created
Explicit/Named	These modules are manually defined by editing the `module-info.java` file
Unnamed	When a JAR is placed on a classpath, unnamed modules are created

When you migrate your applications to Java 9, your application and its libraries become unnamed modules. So, you will need to ensure all the modules are in the module path.

Another thing to be aware of is that your runtime image will not contain the entire JDK. Instead, it will only contain the modules your application requires. It is worth reviewing how the JDK is modularized in Java 9. The following table contains the API specification for the JDK in Java 9:

`jdk.accessibility`	`jdk.attach`	`jdk.charsets`	`jdk.compiler`
`jdk.crypto.cryptoki`	`jdk.crypto.ec`	`jdk.dynalink`	`jdk.editpad`
`jdk.hotspot.agent`	`jdk.httpserver`	`jdk.incubator.httpclient`	`jdk.jartool`
`jdk.javadoc`	`jdk.jcmd`	`jdk.jconsole`	`jdk.jdeps`
`jdk.jdi`	`jdk.jdwp.agent`	`jdk.jlink`	`jdk.jshell`
`jdk.jsobject`	`jdk.jstatd`	`jdk.localedata`	`jdk.management`
`jdk.management.agent`	`jdk.naming.dns`	`jdk.naming.rmi`	`jdk.net`
`jdk.pack`	`jdk.packager.services`	`jdk.policytool`	`jdk.rmic`
`jdk.scripting.nashorn`	`jdk.sctp`	`jdk.security.auth`	`jdk.security.jgss`
`jdk.snmp`	`jdk.xml.dom`	`jdk.zipfs`

The following table contains the API specification for Java SE in Java 9:

`java.activation`	`java.base`	`java.compiler`	`java.cobra`
`java.datatransfer`	`java.desktop`	`java.instrument`	`java.logging`
`java.management`	`java.management.rmi`	`java.naming`	`java.prefs`
`java.rmi`	`java.scripting`	`java.se`	`java.se.ee`
`java.security.jgss`	`java.security.sasi`	`java.sql`	`java.sql.rowset`
`java.transaction`	`java.xml`	`java.xml.bind`	`java.xml.crypto`
`java.xml.ws`	`java.xml.ws`	`java.xml.ws.annotation`

Remember, all applications will have access to java.base as it is in the module path by default.

The following table contains the API specification for JavaFX in Java 9:

`javafx.base`	`javafx.controls`	`javafx.fxml`	`javafx.graphics`
`javafx.media`	`javafx.swing`	`javafx.web`

There are two additional modules:

java.jnlp defines the API for JNLP (Java Network Launch Protocol)
java.smartcardio defines the API for the Java Smart Card Input/Output

For details on any of these modules, visit Oracle's Java? Platform, Standard Edition & Java Development Kit Version 9 API Specification website: http://download.java.net/java/jdk9/docs/api/overview-summary.html.