What are E, K, N, S, T, U, V in Java Generics

If you are wondering what <E>, <K, V>, <N> and so on are called in Java Generics? Well, they are known as "Type Parameters".

Type Parameters are placeholders for data types that are defined when creating generic classes, interfaces, or methods. They are specified inside angle brackets (<>) when defining a generic class, interface, or method.

Examples:

Genetic Interface with Type Parameter E:

interface Payment<E> {
    void process(E payment);
}




Genetic Method with Type Parameter E:

public <E> void printElement(E element) {
    System.out.println(element);
}




Genetic Class with Type Parameter E:

class Container<E> {
    private E item;

    public Container(E item) {
        this.item = item;
    }

    public E getItem() {
        return item;
    }
}

Naming Conventions of Type Parameters:

The Type Parameters are represented by single uppercase letters e.g., E, T, K, V.

Naming Convention	Type Parameter	Usage	Example
E	Element	Used extensively by the Java Collections Framework	List<E>
K	Key	Typically used in key-value pairs or maps	Map<K, V>
N	Number	Often used for numeric types	List<Number>
T	Type	A general-purpose type parameter	Box<T>
V	Value	Commonly used in key-value pairs or maps	Map<String, V>
S, U, V, etc.	2nd, 3rd, 4th types	Used for additional type parameters	Pair<S, T>, Triple<U, V, W>