What's Element in Java?

Question

In javadoc about ArrayList you can read about the method add(E e) where e is an element. What's the differense between elements and objects? I am interested in how the elements are different from objects in Java, not generics .

Answer 1

Elements are no different from Objects in Java.

In real life though

It is a part of good practices used when using Java, but they all design Objects. Knowing that in Java, when writing classes using genericity, you may use the names you want like below

public class MyClass<IChooseTheNameIWant> {} // This is totally valid.
public class MyClass<T> {} // This is valid AND respects good practices.

It is better to follow the good practices to ensure durability/readability (for others) of your code. And this is what the Java language architects did when designing ArrayList.

Generics : How They Work?

Type parameters, also known as type variables, are used as placeholders to indicate that a type will be assigned to the class at runtime. There may be one or more type parameters, and they can be utilized throughout the class, as needed. By convention, type parameters are a single uppercase letter, and the letter that is used indicates the type of parameter being defined. The following list contains the standard type parameters for each use case:

E: Element
K: Key
N: Number
T: Type
V: Value
S, U, V, and so on: Second, third, and fourth types in a multiparameter situation

Answer 2

In that context Element is a Generic Object example: you can not do List<int> instead mus use the class Integer and do List<Integer>

Answer 3

In general, an element is a part of a whole. For example, the number 4 is an element in 1,2,4,8. The number 16 and the string elephant are not.

In Java, the elements of a list can be references to objects, or the special null value that references no object.