Javadoc vs VisualVM

Javadoc creates HTML API documentation from Java source files and is installed with the Java Development Kit (JDK). Its standard doclet describes public and protected Java types and members, including classes, interfaces, constructors, methods, and fields. It can process packages, individual source files, or both, with an option to include subpackages recursively. Alternate doclets can change the content and format of the generated output, while taglets add support for custom tags in documentation comments. The standard doclet includes DocLint to help identify common comment problems, but DocLint does not check conformance or repair errors. Oracle cautions that generated output may pose issues if it is non-conformant or contains executable content such as JavaScript. JDK 25 downloads are listed for Linux, macOS, and Windows. JDK 25 binaries are free under Oracle No-Fee Terms and Conditions through September 2028; later updates use a license that may require fees for production use beyond limited free grants.

VisualVM is a free standalone tool for troubleshooting Java applications in development and production. It combines JDK command-line tools with monitoring for CPU use, garbage collection, heap and metaspace memory, loaded classes, and running threads. Sampling and instrumentation profilers help analyze performance and memory use. For diagnostics, it can capture thread dumps, browse heap dumps, analyze core dumps, and save application data for offline review. VisualVM can list remote Java applications when jstatd runs on the remote host, or connect to applications manually through JMX. Official and third-party plugins extend the tool, and a Security plugin provides a GUI for SSL/TLS settings. The site documents integrations or launchers for Eclipse, IntelliJ IDEA, and Visual Studio Code, plus a third-party NetBeans profiler. It runs on Windows, Linux, and macOS and is distributed as a ZIP archive and a macOS application bundle. The download page lists Oracle JDK and OpenJDK versions 8–26 and GraalVM versions 19–JDK 26. Some third-party plugins may not work after changes introduced in VisualVM 2.0.