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Generic Types in Java¶

Generic Types in Java are a feature that allows developers to specify and work with types (classes and interfaces) as parameters.^[600-developer__java__java-base__Generics.md]

Categories of Generics¶

Generics in Java are primarily categorized into three forms:^[600-developer__java__java-base__Generics.md]

Generic Classes
Generic Interfaces
Generic Methods

Generic Methods¶

A Generic Method introduces its own type parameters, independent of the generic types defined by the class in which it resides.^[600-developer__java__java-base__Generics.md] This allows the method to vary independently of the class, enabling more flexible and type-safe operations.

Bounded Type Parameters ¶

Generic methods can restrict the types they accept using bounded type parameters.^[600-developer__java__java-base__Generics.md] For instance, a method may specify that a type parameter must extend a specific class, such as Number.

Code Example¶

The following example demonstrates a generic class Generic with a type parameter T, alongside a generic method showKeyName that uses a distinct type parameter U bounded by Number:^[600-developer__java__java-base__Generics.md]

class Generic<T> {
    T key;

    public T getKey() {
        return key;
    }

    public <U extends Number> U showKeyName(Generic<U> [container](<./container.md>)) {
        System.out.println("[container](<./container.md>) key :" + [container](<./container.md>).getKey());
        U test = [container](<./container.md>).getKey();
        return test;
    }
}

Java
[[Type Parameters]]
[[Bounded Types]]

Sources¶

600-developer__java__java-base__Generics.md