Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>A few additions to the previous answer:</p> <blockquote> <p>Is the InnerClasses attribute used to store the contained inner/nested classes in the containing class or is it used in the inner/nested classes to refer to the ‘container’ class?</p> </blockquote> <p>The bytecode of every compiled class is stored in a separate .class file. The the actual "inner classes" are not stored in that attribute. As the previous post pointed out, that attribute only points to classes that the compiler knew about when creating the bytecode.</p> <blockquote> <p>Is the InnerClasses attribute in class files sufficient? E.g. Do inner/nested classes have to follow the name mangling with $ or is this just a convention?</p> <p>Is there a way to make a class look like an inner/nested class to the JVM without setting the InnerClasses attribute and does this depend on the JLM vendor? (I remember hearing that IBM's implementation had less strict requirements in some parts.)</p> </blockquote> <p>For both questions, I am not certain. But I think the concept of inner/nested classes is something that the Java language (and hence the Java compiler provides). In the bytecode, there should not be any difference between a class that was declared as a normal public class and some nested or inner class. You could easily try out how an given VM handles this like so:</p> <ul> <li>Create a class with some nested and inner classes</li> <li>Write a little program that tries to load and instantiate one of the inner classes through reflection from outside the scope of defining class. You must use reflection here, because the Java compiler will not allow you to instantiate a nested class that is not in scope! If you can successfully instantiate the class, that is evidence that internally the VM does not handle nested and normal classes differently.</li> </ul> <blockquote> <p>How much does the class loading mechanism of the JVM interact with Java reflection? Would it be possible to make the JVM disagree with the results from Java reflection?</p> </blockquote> <p>I don't understand this last question. Could you explain a bit more what you mean when you say the VM and reflection should disagree?</p>
    singulars
    1. This table or related slice is empty.
    1. POHow can a JVM decide if a class “belongs” (e.g. inner or nested classes) to another class?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USJochen
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POHow can a JVM decide if a class “belongs” (e.g. inner or nested classes) to another class?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTBountyClose
    1. COHi Jochen! 1) I was wondering about the direction of the `InnerClass` attribute, e. g. does it point from the inner class to the containing or the other way around? 2) I'm asking that because it seems to be underspecified in the spec. I'll try to test it as you recommended.
      singulars
      1. PO
      1. USsoc
    2. CO3) The JVM's "own" `ClassLoader` is implemented in native code, while the reflection functionality concerning classes is implemented in Java, largely with comparing and subStringing Strings. I wonder if it is possible to craft a file where the mechanism of the JVM disagrees with Java reflection. E. g. Java reflections says that `A$B` is an inner class of `A` while the JVM says no.
      singulars
      1. PO
      1. USsoc
    3. COI took a quick look and it appears that the InnerClasses attribute is set for BOTH. You can take a look at generated bytecode with Eclipses built in Class File Viewer (right-click on a .class file and select "Open with -> Class File Viewer"). The info written there tells you which is the outer and which is the inner class. So if someone (for example the class loader) would look, it could work it out from there. However, I suspect that this might be something that different compilers do differently. I have checked only with Eclipse/JDT.
      singulars
      1. PO
      1. USJochen
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload