Re: Problems getting generic signatures of generated classes to show via Reflection

  Worked for me. The following code prints java.util.List<java.lang.String>

    final byte[] buff = TestDump.dump();
    Class c = new ClassLoader() { Class c = defineClass("test.Test", 
buff, 0, buff.length); }.c;
   
    Method[] methods = c.getDeclaredMethods();
    System.err.println(methods[0].getGenericReturnType());

  where TestDump class were generated by ASMifier from the following 
source code compiled with Java 1.5:

package test;
import java.util.List;

public class Test {
  private List<String> list;
  public List<String> getList() {
    return list;
  }
}

  regards,
  Eugene


Tatu Saloranta wrote:
> (note: apologies if this email gets sent twice -- I had some issues
> subscribing to the list)
>
> I am trying to generate simple setters and getters, but such that
> return type and arguments would contain proper generic signature. This
> is necessary as classes are further introspected by another library
> which needs to know generic type information for its handling.
> As far as I know, code should work (I have sample later); and when
> using ASM's ClassVisitor, things look ok.
> However, when trying to access generic type information via reflection
> (Class.getDeclaredMethods(), getDeclaredFields()), no generic type
> information is seen.
> It would seem as if the way ASM adds attributes was somehow not
> compatible with regular JDK's expectations.
>
> Code I use is quite simple, along lines of:
>
> ---
>        final String className = "TestClass";
>        final String internalClass = "TestClass";
>
>        ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
>
>        cw.visit(V1_2, ACC_PUBLIC + ACC_SUPER, internalClass, null,
> "java/lang/Object", new String[0]);
>        cw.visitSource("TestClass.java", null);
>
>        // default constructor:
>        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V",
> null, null);
>        mv.visitCode();
>        mv.visitVarInsn(ALOAD, 0);
>        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
>        mv.visitInsn(RETURN);
>        mv.visitMaxs(0, 0); // don't care (real values: 1,1)
>        mv.visitEnd();
>
>        // one field
>        String fieldDesc = "Ljava/util/List;";
>        String fieldSig = "Ljava/util/List<Ljava/lang/String;>;";
>        final String fieldName = "foo";
>        FieldVisitor fv = cw.visitField(ACC_PUBLIC, fieldName,
> fieldDesc, fieldSig, null);
>        fv.visitEnd();
>
>        // then one getter (removed for now)
>
>        cw.visitEnd();
>
> ---
>
> and I even checked with utility class to see what ASM thinks is proper
> way to generate classes (using a JDK compiled similar bean as base).
> But types that Method and Field show are raw type erased classes.
>
> Any guesses as to what I might be doing wrong?
>
> -+ Tatu +-
>

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