Running Javaflow

[puff li]

Hi Everyone,

I am writing a model checker and need to store and restore state of programs. After googling, I found Apache Javaflow appears to be a neat tool to do it. However, I got problem running it. Can someone kindly help?

I download the commons-javaflow-2006.jar and asm-3.3.jar and try to test it with the example on Apache: http://commons.apache.org/sandbox/javaflow/tutorial.html
This is the code:

  
import org.apache.commons.javaflow.*;

public class MyRunnable implements Runnable{
  public void run() {
    System.out.println("started!");
    for( int i=0; i<10; i++ )
      echo(i);
  }
  private void echo(int x) {
    System.out.println(x);
    Continuation.suspend();
  }
  
  public static void main(String[] args) {
  	Continuation c = Continuation.startWith(new MyRunnable());
  	System.out.println("returned a continuation");
  }
}  

I write build.xml like this:

<project name="MyProject" default="run">

	<target name="clean">
		<delete includeemptydirs="true">
			<fileset dir="class" includes="**/*"/>
		</delete>
	</target>
	
	<taskdef name="javaflow" classname="org.apache.commons.javaflow.ant.AntRewriteTask">
		<classpath>
			<pathelement location="lib/javaflow.jar"/>
		</classpath>
	</taskdef>
	
	<target name="build" depends="clean">
		<mkdir dir="class"/>
		
		<javac srcdir="." destdir="class">
			<classpath>
				<pathelement location="lib/javaflow.jar"/>
				<pathelement location="lib/asm.jar"/>
			</classpath>
		</javac>
		
		<javaflow srcdir="." dstdir="class">
			<include name="**/*.class"/>
		</javaflow>
		
	</target>
	
	<target name="run" depends="build">
		<java classname="MyRunnable"  fork="true" dir="class/class">
			<classpath>
				<pathelement location="lib/javaflow.jar"/>
				<pathelement location="lib/asm.jar"/>
			</classpath>
		</java>
	</target>
</project>
 

Below is the output:


Buildfile: build.xml

clean:

build:
[javac] Compiling 1 source file to /home/lihao/Desktop/JavaflowTest/class
[javaflow] Rewriting /home/lihao/Desktop/JavaflowTest/class/MyRunnable.class

run:
[java] Exception in thread "main" java.lang.NoClassDefFoundError: MyRunnable
[java] Caused by: java.lang.ClassNotFoundException: MyRunnable
[java] at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
[java] at java.security.AccessController.doPrivileged(Native Method)
[java] at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
[java] at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
[java] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
[java] at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
[java] at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
[java] Could not find the main class: MyRunnable. Program will exit.
[java] Java Result: 1

BUILD SUCCESSFUL
Total time: 1 second

And the compilation seems fine. But when running, it turns out "Could not find the main class".
We I run the instrumented Myrunnable.class from commandline, it report error like this:


Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/javaflow/bytecode/Continuable
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.javaflow.bytecode.Continuable
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:334)
... 12 more
Could not find the main class: MyRunnable. Program will exit.


I don't understand why. I have included every possible lib in my classpath. Please help!

Thanks.

[Campbell Ritchie]

How did you set the CLASSPATH?

[puff li]

Campbell Ritchie wrote:How did you set the CLASSPATH?

Thanks for reply~

In build.xml:

<javac srcdir="." destdir="class">
			<classpath>
				<pathelement location="lib/javaflow.jar"/>
				<pathelement location="lib/asm.jar"/>
			</classpath>
</javac>

<java classname="MyRunnable"  fork="true" dir="class/class">
			<classpath>
				<pathelement location="lib/javaflow.jar"/>
				<pathelement location="lib/asm.jar"/>
			</classpath>
</java>

Is it right?

[David Newton]

I'd assume the classname needs to be fully qualified.

[Campbell Ritchie]

And does your classpath still include the . for current directory? If you are putting your compiled files into the "class" directory, is that in the classpath?

[puff li]

David Newton wrote:I'd assume the classname needs to be fully qualified.

What do you mean by fully qualified?

[puff li]

Campbell Ritchie wrote:And does your classpath still include the . for current directory? If you are putting your compiled files into the "class" directory, is that in the classpath?

Wow, it works when I add "class" directory in the classpath!

Thank you so much Campbell!!! Thank you David as well!!! I spent a whole day yesterday working on it!

So can you explain why I have to add "class" directory in the classpath. It just contains one compiled file. I specified to run it as main class in

 <java classname="MyRunnable" dir="class/class">   

why should I add it again? I suppose classpath means where needed libraries are located?

[Campbell Ritchie]

The classpath variable tells the JVM where to look for .class files. If you have your .class files in the "class" directory, you have to instruct it to try there for .class files.