Can any data types be used in generic parameters?

In Java, primitive data types (such as int, boolean, double) cannot be used as parameters in generics. Instead, their corresponding wrapper classes (Integer, Boolean, Double, etc.) should be used.

This is because generics in Java are implemented through type erasure and only work with object types.

Example:

List<Integer> numbers = new ArrayList<>(); // correct
List<int> numbers = new ArrayList<>(); // compile error

Thus, you can use any classes and interfaces, but not primitives directly.