Re: NullPointerException in setMaxStack()

Hmm, maybe i misread your code, and the problem is the other way. Aren't you 
appending statements after the return statement?

----- Original Message ----- 
From: "Eduardo Guerra" <[email protected]>
To: <[email protected]>
Sent: Friday, April 18, 2008 12:37 PM
Subject: NullPointerException in setMaxStack()


> Hi!
>
> I'm trying to put some code for log each line of code: There is the code:
>
> ClassParser cp = new ClassParser(new
> ByteArrayInputStream(classFileBuffer),className+".java");
>
> JavaClass jc = cp.parse();
> ClassGen cg = new ClassGen(jc);
> InstructionFactory factory = new InstructionFactory(cg);
> ConstantPoolGen cpg = new ConstantPoolGen(jc.getConstantPool());
>
> ObjectType pStream = new ObjectType("java.io.PrintStream");
>
> for(int i = 0; i < cg.getMethods().length; i++){
> MethodGen mg = new MethodGen(cg.getMethods()[i], jc.getClassName(), cpg);
> InstructionList il = mg.getInstructionList();
>
> for(LineNumberGen lng : mg.getLineNumbers()){
> InstructionHandle ih = lng.getInstruction();
> ih = il.append(ih,factory.createFieldAccess("java.lang.System",
> "out", pStream, Constants.GETSTATIC));
> ih = il.append(ih,new PUSH(cpg,"Classe "+jc.getClassName()+ "
> metodo " + cg.getMethods()[i].getName() +  " linha " +
> lng.getSourceLine()));
> ih = il.append(ih,factory.createInvoke("java.io.PrintStream",
> "println", Type.VOID, new Type[]{Type.STRING},
> Constants.INVOKEVIRTUAL));
> }
>
> mg.setInstructionList(il);
> mg.setMaxStack();
> mg.setMaxLocals();
> cg.replaceMethod(cg.getMethods()[i], mg.getMethod());
> }
>
> cg.setConstantPool(cpg);
> JavaClass newClass = cg.getJavaClass();
>
> return newClass.getBytes();
>
>
> For some methods, the setMaxStack() throws NullPointerException with
> this stacktrace:
>
> java.lang.NullPointerException
> at 
> org.apache.bcel.generic.FieldOrMethod.getSignature(FieldOrMethod.java:54)
> at 
> org.apache.bcel.generic.FieldInstruction.getFieldType(FieldInstruction.java:71)
> at 
> org.apache.bcel.generic.FieldInstruction.getType(FieldInstruction.java:64)
> at 
> org.apache.bcel.generic.FieldInstruction.getFieldSize(FieldInstruction.java:57)
> at org.apache.bcel.generic.GETSTATIC.produceStack(GETSTATIC.java:47)
> at org.apache.bcel.generic.MethodGen.getMaxStack(MethodGen.java:928)
> at org.apache.bcel.generic.MethodGen.setMaxStack(MethodGen.java:814)
> at teste.IntrumentatorAdaptor.transform(IntrumentatorAdaptor.java:54)
> at 
> sun.instrument.TransformerManager.transform(TransformerManager.java:169)
> at 
> sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:365)
> at java.lang.ClassLoader.defineClass1(Native Method)
> at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
> at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
> at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
> at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
> at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
> at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
>
>
> Thanks in advance for any help!!!
>
> Eduardo Guerra
>
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