How Do Generic Return Types Work in Java?

Understanding Generic Return Types in Java

Java allows developers to define methods with generic return types, which can adapt to different types of data at runtime. This feature is commonly employed to create flexible and reusable code.

Consider the following Java method:

public <E extends Foo> List<E> getResult(String s);

where Foo represents a user-defined class. This method may seem confusing at first as it appears to have two return types: List and E. However, this is not the case.

The part of the method signature is known as a type parameter. It allows the method to accept any type E that inherits from the Foo class. This is a form of generic polymorphism.

The actual return type of the method is List, which means a list containing elements of type E. Since E can be any subtype of Foo, the method can return a list of Foo objects or any of its derived classes.

In summary, the getResult method has a single return type, which is a List containing elements of a type that extends Foo. The type parameter E provides flexibility and allows the method to handle different data types seamlessly.

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