Arrays - The Java Language Specification - page 294

Chapter 10. Arrays
In the Java programming language, arrays are objects (§ 4.3.1 ) , are dynamically created, and
may be assigned to variables of type Object (§ 4.3.2 ) . All methods of class Object may be in-
voked on an array.
An array object contains a number of variables. The number of variables may be zero, in
which case the array is said to be empty . The variables contained in an array have no names;
instead they are referenced by array access expressions that use non-negative integer index
values. These variables are called the components of the array. If an array has n components,
we say n is the length of the array; the components of the array are referenced using integer
indices from 0 to n - 1, inclusive.
All the components of an array have the same type, called the component type of the array.
If the component type of an array is T , then the type of the array itself is written T [] .
The value of an array component of type float is always an element of the float value set
(§ 4.2.3 ) ; similarly, the value of an array component of type double is always an element of
the double value set. It is not permitted for the value of an array component of type float
to be an element of the float-extended-exponent value set that is not also an element of the
float value set, nor for the value of an array component of type double to be an element of the
double-extended-exponent value set that is not also an element of the double value set.
The component type of an array may itself be an array type. The components of such an ar-
ray may contain references to subarrays. If, starting from any array type, one considers its
component type, and then (if that is also an array type) the component type of that type, and
so on, eventually one must reach a component type that is not an array type; this is called
the element type of the original array, and the components at this level of the data structure
are called the elements of the original array.
There are some situations in which an element of an array can be an array: if the element
type is Object or Cloneable or java.io.Serializable , then some or all of the elements may be arrays,
because any array object can be assigned to any variable of these types.
10.1. Array Types
Array types are used in declarations and in cast expressions (§ 15.16 ).
An array type is written as the name of an element type followed by some number of empty
pairs of square brackets [] . The number of bracket pairs indicates the depth of array nesting.