I always thought that any array type is like a different class but it seems like any reference type arrays are also considered an object of Object[] and their superclasses' array form. (Is this exactly right?)
Consider the following array
Integer[] numbers = { 20, 15, 10, 5 };
When I pass this array to Arrays.sort which expects an Object[] value, it works fine. But an Object doesn't have any method to compare, how does it know which compare method to use?
Integer implements Comparable<Integer> which defines a natural ordering on Integers. Calling sort without a Comparator relies on the elements of the array to implement Comparable, and uses the compareTo method of that interface.
All elements in the array must implement the Comparable interface and also they must be mutually comparable. If you are passing to this method an array containing elements that don't fulfill these requirements, you'll get exceptions. It doesn't care what you pass. It attempts to cast each element that required comparison to Comparable and calls the compareTo method, passing to it another object.@InsignificantPerson Since you can assign a Cat[]` to an Animal[] variable, I think you can say that Cat[] extends Animal[]. For example : Cat[] ca = new Cat[5]; Animal[] aa = ca; works.Arrays.sort is used for primitive types and the Object as well.
As per the array elements type those are being sorted by using sort1 but these sort1 methods are private.
If you are tying to sort int array. So you will use method sort(int[] a). It will call the private method sort1:
private static void sort1(int x[], int off, int len) {...}
And this method description is Sorts the specified sub-array of integers into ascending order.
mergeSort method.But When you look at Integer class file, it implements Comparable<Integer> (Remember although it's subclass of Object):
public final class Integer extends Number implements Comparable<Integer>
So here you don't want to use the Arrays.sort method. By using the compareTo(Integer anotherInteger) method the array can be sorted.
