小编Sti*_*ver的帖子

我在嵌套类中的方法参数注释中遇到了一个奇怪的效果.看起来非常像编译器问题.有关重现的详细信息和步骤,请参见下文.

使用javac编译以下类(我使用了javac 1.7.0_51).请注意带注释的参数"boolean param3".

import java.lang.annotation.Annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

public class TestAnnotations {

    public String a;

    @Retention(RetentionPolicy.CLASS)
    @interface MyAnnotation {}

    protected class TestInner {

        public TestInner(String param1, Object param2, 
                                     @MyAnnotation boolean param3) {}

        public void accessField() {
            System.out.println(TestAnnotations.this.a);
        }
    }
}

然后用javap检查嵌套类(即javap -p -v -c TestAnnotations $ TestInner.class).它的构造函数如下所示.

 public test.TestAnnotations$TestInner(test.TestAnnotations, java.lang.String, 
                                                java.lang.Object, boolean);
   flags: ACC_PUBLIC
   Code:
     stack=2, locals=5, args_size=5
        0: aload_0
        1: aload_1
        2: putfield      #1                  // Field this$0:Ltest/TestAnnotations;
        5: aload_0
        6: invokespecial #2                  // Method java/lang/Object."<init>":()V
        9: return …