If you are looking to analyze and visualize the call relationships in your Java applications, the Java Call Graph Utilities is a suite that stands ready to assist. This blog will walk you through the installation, compilation, and running of both static and dynamic call graph generators, while also addressing common issues you might encounter along the way.

What Are Java Call Graph Utilities?

The Java Call Graph Utilities provide two primary functionalities:

• Static Analysis: Using javacg-static, you can analyze JAR files to discover the relationships between method calls in your codebase.
• Dynamic Analysis: With javacg-dynamic, you track method invocations during runtime, allowing you to see caller-callee relationships reflected in real time.

Installation and Compilation

Before you can use the Java Call Graph Utilities, you will need to install Maven and compile the package. Follow these steps:

• Install Maven on your system.
• Open your terminal and navigate to the project’s root directory.
• Run the command:

mvn install

• This command compiles the package and creates a target directory containing the following jars:
• javacg-0.1-SNAPSHOT.jar: Contains classes for both static and dynamic analysis.
• javacg-0.1-SNAPSHOT-static.jar: The executable jar for static call graph generation.
• javacg-0.1-SNAPSHOT-dycg-agent.jar: The executable jar for dynamic call graph generation.

Running the Call Graph Generators

Static Call Graph Generation

To generate a static call graph, use the following command:

java -jar javacg-0.1-SNAPSHOT-static.jar lib1.jar lib2.jar ...

The output will include caller-caller relationships in this format:

M:class1:method1(arg_types) (typeofcall)class2:method2(arg_types)

Where typeofcall indicates the type of method call, such as:

• M for invokevirtual calls
• I for invokeinterface calls
• O for invokespecial calls
• S for invokestatic calls
• D for invokedynamic calls

Dynamic Call Graph Generation

Running the dynamic generator is a bit more intricate, as you need to instrument methods. Here’s how to do it:

Use this command to run your application with dynamic analysis:

java -Xbootclasspath:... -javaagent:javacg-0.1-SNAPSHOT-dycg-agent.jar=incl=mylib.*,mylib2.*,java.nio.* -jar yourapplication.jar

The javacg-dynamic tool will then capture method invocation pairs and produce output that looks like:

class1:method1 class2:method2 numcalls

It also generates a calltrace.txt file with timestamps of method entries and exits, allowing you to profile the execution time of methods.

Understanding the Code Analogy

Think of a call graph as a map of a city where:

• Each class is represented as a unique neighborhood.
• Each method functions as a street within those neighborhoods.
• The calls are the connections or roads that link one neighborhood to another, showing you how one area interacts with others.

Just as you can navigate from one neighborhood to another via specific streets, the call graph helps you trace how methods in different classes interact with each other!

Troubleshooting

While using the Java Call Graph Utilities, you might encounter some common issues. Below are tips on how to resolve them:

• Ensure that your Java version is compatible with the Java Call Graph Utilities.
• If you face issues with the dynamic analyzer, remember that it may not work as expected with multithreaded applications.
• If you’re using reflection to invoke methods, the static analyzer won’t capture those calls.

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Conclusion

Utilizing static and dynamic call graph generators can profoundly enhance your understanding of method interactions in Java applications. By knowing how to compile and execute these tools efficiently, you will be better equipped to maintain and optimize your Java code effectively.

At fxis.ai, we believe that such advancements are crucial for the future of AI, as they enable more comprehensive and effective solutions. Our team is continually exploring new methodologies to push the envelope in artificial intelligence, ensuring that our clients benefit from the latest technological innovations.