One of the restrictions with Java Generics is that they must be instantiated with a reference type. This means you cannot use a primitive type such as int, char or double. Instead, we must use its corresponding non-primitive type (eg. Integer, Character, Double).
Luckily, Java automatically converts a primitive type to its corresponding reference type; this is known as autoboxing..
So for example, when we place an item into our container of primitive type, such as the number 50, converts it an equivalent refernece type.
Thus we have
int morphing into
intContainer.add(50); // is actually doing this... intContainer.add(new Integer(50));
In contrast, auto-unboxing occurs when retrieving that same item from our collection.
// from Integer to int int i = intContainer.getData();
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