Collections - The Java Programming Language - page 901

21.12. The Arrays Utility Class
The class Arrays provides useful static methods for dealing with arrays.
Most of these methods have a full complement of overloads: one for ar-
rays of each primitive type (except boolean for searching and sorting) and
one for Object arrays. There are also two variants of some methods: one
acting on the whole array and one acting on the subarray specified by
two supplied indices. The methods are
• sort Sorts an array into ascending order. The exact algorithm is
not specified other than it must be stable for objects (that is, equal
objects don't get reordered because of the sort). A good imple-
mentation would use a technique that is not worse than O(nlogn)
• binarySearch Searches a sorted array for a given key. Returns the
key's index, or a negative value encoding a safe insertion point
(as for the method Collections.binarySearch described previously).
There are no subarray versions of these methods.
• fill Fills in the array with a specified value.
• equals and deepEquals Return true if the two arrays they are passed
are the same object, are both null , or have the same size and
equivalent contents. There are no subarray versions. The equals
method for Object[] uses Object.equals on each non- null element
of the array; null elements in the first array must be matched
by null elements of the second. This does not treat nested arrays
specially, so it cannot generally be used to compare arrays of ar-
rays. The deepEquals method checks for equivalance of two Object[]
recursively taking into account the equivalence of nested arrays.
• hashCode and deepHashCode Return a hash code based on the con-
tents of the given array. There are no subarray versions. The deep-
HashCode method computes a hash code for an Object[] recursively
taking into account the contents of nested arrays.