I think I found a bug in the ClassFile API but since I'm new to it, before
creating one in Jira, I wanted to double-check I'm not doing something
stupid... could someone please confirm?
Consider this simple test class:
import java.lang.annotation.*;
import java.lang.classfile.*;
import java.nio.file.Path;
public class Test {
public static void main(String[] args) throws Exception {
final String filename = args.length > 0 ? args[0] : "Example.class";
final Path path = Path.of(filename);
final ClassFile classFile = ClassFile.of();
final ClassModel classModel = classFile.parse(path);
classModel.forEach(classElement -> {
switch (classElement) {
case MethodModel method when
method.methodName().equalsString("<init>") ->
System.out.println(String.format("%s: method \"%s\":
runtime visible type annotations: %s",
filename, method.methodName(),
method.findAttribute(Attributes.runtimeVisibleTypeAnnotations())));
default -> { }
}
});
}
}
class Example {
Example(Object o) {
String s = (@Anno String)o;
}
}
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE_USE)
@interface Anno { }
If you compile and run this test it doesn't find any type annotation
attribute on the Example constructor:
$ javac Test.java && java Test
Example.class: method "<init>": runtime visible type annotations:
Optional.empty
Yet javap shows that there is one (as expected):
$ javap -verbose Example
...
Example(java.lang.Object);
descriptor: (Ljava/lang/Object;)V
flags: (0x0000)
Code:
stack=1, locals=3, args_size=2
0: aload_0
1: invokespecial #1 // Method
java/lang/Object."<init>":()V
4: aload_1
5: checkcast #7 // class java/lang/String
8: astore_2
9: return
LineNumberTable:
line 24: 0
line 25: 4
line 26: 9
RuntimeVisibleTypeAnnotations:
0: #15(): CAST, offset=5, type_index=0
Anno
Thanks,
-Archie
--
Archie L. Cobbs
