While we are at generics, What is the difference b...

# announcements

[andylamax]

While we are at generics, What is the difference between fun <T> Foo() and fun <T:Any> Foo() ?

So far I have just been using IntelliSense suggestions. I wan't to understand more. Any deep explanation?

[diesieben07]

First one allows nullable types (e.g. String?) for T, the 2nd one does not.

[araqnid]

T: Any specifies that T is a non-null type (Any? is the ultimate supertype)

[andylamax]

so, there is no difference between fun <T:Any?> Foo() and fun <T> Foo() ?

[araqnid]

right, <T> is effectively <T:Any?>

[andylamax]

Then, I am glad. My thirst is quenched. Thank you

[Md Sajid Shahriar]

If we see the decompiled byte code to java(wanted to post the byte code but this is much more readable) for

fun <T:Any> foo(t:T)

public final void foo(@NotNull Object t) {
   Intrinsics.checkParameterIsNotNull(t, "t");
}

fun <T:Any?> foo(t:T)

public final void foo(Object t) {
}

fun <T> foo(t:T)

public final void foo(Object t) {
}

fun <T> foo(t:T?)

public final void foo(@Nullable Object t) {
}

So yeah to the compiler is basically the same for <T:Any?> and <T>