.class and .length - where do they come from?

Question

hi,
I was wondering about the field .length, which you can invoke on an array
int anIntArray[] = new int[10];
System.out.println("length="+anIntArray.length);
this would produce the output
length=10
But where does this field come from? I can not find it in the Object-class.
The same thing applies to the .class:
System.out.println("String's class="+String.class);
would produce the output
String's class=class java.lang.String
Where does the .class in String.class come from? And is it a field, an operator or something else?
Are there any other "hidden" fields or operators, which are not keywords or come from Object?

Answer 1

Arrays are objects so they can have fields. The length field defined in the classes for the arrays. These classes are created on the fly by the JVM so you won't be able to see the fields in any source code or JavaDoc documentation.
'.class' isn't a field at all. When you put '.class' on the end of a class name what you get is a class literal. Class literals evaluate to an instance of the Class class. Try compiling a small example using '.class' and then take a look at the produced java bytecode using 'javap -c'.