How to Get a Comprehensive List of Classes Loaded in the Java Virtual Machine (JVM)?

Java Get List of Classes in JVM

Obtaining a comprehensive list of classes loaded in the Java Virtual Machine (JVM) can be a valuable resource for troubleshooting, analyzing performance, and exploring the structure of an application. However, as you have mentioned, certain classes may not be loaded initially and need to be dynamically retrieved.

While Java does not provide a straightforward programmatic approach to achieve this, there exists an alternative method that offers a comprehensive view of the loaded classes.

The java -verbose:class command-line option can be utilized to enable detailed logging of class loading activity. When executed, the JVM generates detailed output that includes the following information:

• Names of the opened JAR files from which classes are loaded
• Names of the loaded classes and their respective locations within the JAR files

For instance, running the following command:

java -verbose:class ....

Generates output similar to this:

[Opened /usr/java/j2sdk1.4.1/jre/lib/rt.jar]
[Opened /usr/java/j2sdk1.4.1/jre/lib/sunrsasign.jar]
[Opened /usr/java/j2sdk1.4.1/jre/lib/jsse.jar]
[Opened /usr/java/j2sdk1.4.1/jre/lib/jce.jar]
[Opened /usr/java/j2sdk1.4.1/jre/lib/charsets.jar]
[Loaded java.lang.Object from /usr/java/j2sdk1.4.1/jre/lib/rt.jar]
[Loaded java.io.Serializable from /usr/java/j2sdk1.4.1/jre/lib/rt.jar]
[Loaded java.lang.Comparable from /usr/java/j2sdk1.4.1/jre/lib/rt.jar]
[Loaded java.lang.CharSequence from /usr/java/j2sdk1.4.1/jre/lib/rt.jar]
[Loaded java.lang.String from /usr/java/j2sdk1.4.1/jre/lib/rt.jar]

By examining this output, you can identify the loaded classes and their respective packages. This technique provides a comprehensive overview of the classes loaded in the JVM, assisting in debugging, monitoring, and analyzing Java applications. For more information on the java -verbose:class option, refer to the official Oracle documentation.

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