Thread: The implementation of a function with generic return type, returns a specific class, is this a good practice?

Consider the following Class structure

public interface Base {
}
 
public class C1 implements Base {
}
 
 
public interface Repo {
    <T extends Base> T get();
}
 
public class C1Repo implements Repo{
    @Override
    public C1 get() {
        return new C1();
    }
}

Repo interface has a function that returns <T extends Base>, but my implementation returns a specific C1 class.
IntelliJ warns "Unchecked overriding: return type requires unchecked conversion. Found 'org.example.C1', required 'T' ". Is this okay? If not how would I restructure this composition?

the compiler can't guarantee that C1 is compatible with T, which results in the warning

--- Update ---

check this https://waytojava.com/java/generics

It's understandable that you're seeking clarity on this matter. The warning from IntelliJ is indicating a potential issue with type safety. Let's break down what's happening and suggest a solution.

In your current implementation, `C1Repo` implements the `Repo` interface, which mandates a generic return type `<T extends Base>` for the `get()` method. However, in `C1Repo`, you're specifying that the method returns a specific class, `C1`.

This creates a mismatch between what the interface promises (`T extends Base`) and what the implementing class provides (`C1`). While it compiles, it bypasses compile-time type checks, potentially leading to runtime errors if the returned type doesn't match expectations.

To address this and ensure type safety, you can modify the `Repo` interface to directly specify the return type:

```java
public interface Repo {
Base get();
}
```

With this change, any class implementing `Repo` must return an instance of `Base` or its subtypes. Your `C1Repo` implementation would then look like this:

```java
public class C1Repo implements Repo {
@Override
public C1 get() {
return new C1();
}
}
```

Certainly, here's the revised last paragraph:

This modification ensures that the return type matches the interface's contract, eliminating the warning and ensuring type safety at compile time. Now, any implementation of `Repo` must adhere to returning a `Base` or its subclass, which aligns with the interface's intention. If you need further help with Java assignment, feel free to explore resources available online like ProgrammingHomeworkHelp.com.