jdeps

jdeps is a command-line utility included with the Oracle JDK and OpenJDK. Its primary function is to analyze Java class files and display the dependency information. Specifically, jdeps can show which packages a given class or JAR file depends on, and conversely, it can identify which classes or JAR files depend on a given package. This information is crucial for understanding the relationships between different parts of a Java project or library.

The tool can be used to identify package-level dependencies, which is particularly useful when migrating code to different Java versions or modules. By running jdeps on a set of JAR files, developers can get a clear picture of external dependencies, helping to avoid potential runtime errors or compatibility issues. The output of jdeps can be presented in various formats, including a simple list of dependencies or a more structured output that details the source of each dependency.

jdeps is part of the Java Development Kit and is available once the JDK is installed. It operates by inspecting the class files' metadata, specifically the constant pool entries that reference other classes and packages. This analysis helps developers in tasks such as dependency management, code refactoring, and optimizing application build processes. It's a valuable tool for maintaining the integrity and clarity of Java applications.