Java 2 Graph

This program generates a control flow graph of a given Java method.

It uses Apache BCEL to parse Java Bytecode files.

Author: Andreas Fuchs

Setup and Usage

Clone from GitHub repository:

$ git clone https://github.com/wwu-pi/java2graph
$ cd java2graph

Compile the sources:

$ cd j2g
$ mvn clean compile

The Main class requires some arguments:

-c the full qualified class name
-mn the method name
-ms the method signature
-o the output directory where to generate the graph file to

If a class in not part of your JRE, you can specify an additional class path with:

-cp /extra/class/path

For example, to generate the control flow graph for a method equals of the java.lang.String class that compares itself to another Object you can use:

-c java.lang.String
-mn equals
-ms (Ljava/lang/Object;)Z
-o /path/to/output

Note that a method in a class is identified by its method name (e.g. equals) and method signature (e.g. (Ljava/lang/Object;)Z for a method with one argument of type java.lang.Object and a boolean (Z) return type).

You can find the method structure with javap:

For example, to find it for all java.lang.String methods:

javap -v -c java.lang.String

You will get something like this:

public static java.lang.String valueOf(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Ljava/lang/String;
    flags: ACC_PUBLIC, ACC_STATIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: ifnonnull     9
         4: ldc           #12                 
         6: goto          13
         9: aload_0
        10: invokevirtual #459                
        13: areturn
      StackMapTable: number_of_entries = 2
        frame_type = 9 /* same */
        frame_type = 67 /* same_locals_1_stack_item */
          stack = [ class java/lang/String ]
      LineNumberTable:
        line 2994: 0

Then the method signature of the method named valueOf with a single parameter of type java.lang.Object is given in descriptor with (Ljava/lang/Object;)Ljava/lang/String;

Run the Program

In order to run the program, you must be in the j2g folder.

You can run the program with the following command:

$ mvn exec:java -Dexec.mainClass="j2g.Main" -Dexec.args="-c your.Class -mn yourMethodName -ms ()V -o /your/output/directory"

For example, to generate an output to C:/_J2G/output for the method equals with the signature (Ljava/lang/Object;)Z of the class java.lang.String, you run:

$ mvn exec:java -Dexec.mainClass="j2g.Main" -Dexec.args="-c java.lang.String -mn equals -ms (Ljava/lang/Object;)Z -o C:/_J2G/output"

Eclipse Project Import

The project can be imported into Eclipse using the following steps:

(1) Clone from repository as explained above.

(2) In Eclipse Menu: File -> Import...

(3) In Import Wizard select: General -> Existing Projects into Workspace and click Next

(4) In Import WIzard Select root directory: specify path where you have cloned the repository to (you might have to select option Search for nested projects)

(5) Click Finish