Question/Errata for OCP: Oracle Certified Professional Java SE 8 Programmer II Study Guide page 554

[Guillaume Bailly]

Hi,

On page 554 question 6, is it really correct to say "Line 7 creates the Hello class with the generic type Object since no type is specified"? I ask this because the compiler can infer that the type T is String because of the parameter passed to the constructor.

Thanks,
Guillaume

[Jeanne Boyarsky]

Guillaume,
You're right. It's not. All three of these compile. Some with warnings, but they still compile.

Hello h1 = new Hello<String>("hi");
Hello h2 = new Hello("hi");
Hello<String> h3 = new Hello<String>("hi");
Hello<String> h4 = new Hello("hi");

[Jeanne Boyarsky]

Three years later, I'm going through the errata in detail to fix them for the Java 11 book. (We are further along than it appears. I did my harder chapters first.)

It turns out this was not an errata. The generic parameter isn't used here. So even though it is in a class with a generic parameter, that doesn't apply to the new object.

System.out.print(new Hello("there"));