And be careful about spelling; array and Array mean different things in Java. As Jesper says, you are using the array operators  not a class called "array" (nor "Array"). Pushkar Choudhary, you are right to say
I'm not sure if this statement is correct.
Joined: Nov 11, 2009
so array is only a kind of data structure
it is not a class
yes, there are some classes which contain methods for manipulating arrays. like class Arrays in java.util package
but there is an instance variable of name length of class name<idon'tknow> which tells you about the no. of elements in an array
then where is it come from?
is it from java.util.Arrays?
array is the only built in collection in Java. This built-in Java array is declared and constructed differently from most of the other java objects. It is a subclass of java.lang.Object, it implements both Serializable and Cloneable interfaces. We can't find a class definition for it in any of the Java Platform class. It's definition is built-in Java language!
Since array is inherited from java.lang.Object. Therefore, it understands all the methods of Object class. Besides the java.lang.Object methods, it also has its own accessible member variable length