java - Why we call unbounded wild-card parameterized type as reifiable? -

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i reading through angelikalangerdoc. reading after gap of 3 days. in earlier lesson, learnt that, arrays of unbounded wild card allowed created. studied unbounded wild-card parameterized types called reifiable types. when searched definition of reifiable type, states that, type type information known @ run-time called reifiable type. picking code snippet article.

pair<?,?>[] inipair = new pair<?,?>[10];

i have following confusion in mind.

  1. why unbounded wild-card parameterized type called reifiable?
  2. in example above, how type information known?

i know it's basic question. trying refresher on track of generics. can elaborate on issue?

since java compiler replace unbounded type parameters object.
according type erasure

to implement generics, java compiler applies type erasure to:

1.replace type parameters in generic types bounds or object if type parameters unbounded. produced bytecode, therefore, contains ordinary classes, interfaces, , methods.

2.insert type casts if necessary preserve type safety.

3.generate bridge methods preserve polymorphism in extended generic types.

the term reifiable according javadoc

a reifiable type type type information available @ runtime. includes primitives, non-generic types, raw types, , invocations of unbound wildcards.


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