Parameterized class without parameters?

Question

In an Android framework I am trying to understand, I find a statement like this:

public Call<GeneralResponseSO> performApiCall(/*...*/) {
    // ...
}

But GeneralResponseSO is defined like this:

public class GeneralResponseSO<T> {
    // ...
}

Shouldn't the api method specify which type T is? I can't seem to grasp why the compiler doesn't give an error, and what type T then is.

Or does the compiler do magic to filter out all the generics from the class? So that all variables/methods that use T are removed? I wouldn't expect the Java compiler to perform such magic though.

https://stackoverflow.com/questions/2770321/what-is-a-raw-type-and-why-shouldnt-we-use-it — JB Nizet, Dec 27 '18 at 10:19
Possible duplicate of [What is a raw type and why shouldn't we use it?](https://stackoverflow.com/questions/2770321/what-is-a-raw-type-and-why-shouldnt-we-use-it) — vrwim, Dec 27 '18 at 11:02

score 2 · Answer 1 · answered Dec 27 '18 at 10:20

A generic class / interface without type parameter is Raw type.

Raw type is unchecked during compile (and you may see warning in IDE such as Intellij) and may cause exception at runtime.

Note: Example.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details.

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Parameterized class without parameters?

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