the "Integer" datatype in java?

Question

import java.util.ArrayList;
import java.util.Collections;

public class MyClass {
public static void main(String[ ] args) {
ArrayList<Integer> nums = new ArrayList<Integer>();
nums.add(3);
nums.add(36);
nums.add(73);
nums.add(40);
nums.add(1);

Collections.sort(nums);
System.out.println(nums);
}
}
here in ArrayList we are defining the type of values stored inside the list are of integer type...
but why we are writing
ArrayList<Integer> and not ArrayList<int> ?

Answer 1

Integer is a class while int is a primitive data type. These class is also called a Wrapper Class

ArralyList doesnt accept or stores primitive data types like int but accepts only objects like Integer. the reason behind is that ArrayList is implemented to use objects only.

Answer 2

thanks