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Wildcard (Java)
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<p>In the <a href="/facts/Java_/9ScgFyAL">Java programming language</a>, the wildcard ? is a special kind of type argument that controls the <a href="/facts/Type_safety/WxmEKq8R">type safety</a> of the use of <a href="/facts/Generics_in_Java/j8nFhEKq">generic</a> (parameterized) types. It can be used in variable declarations and instantiations as well as in method definitions, but not in the definition of a generic type. This is a form of <i>use-site</i> <a href="/facts/Variance_annotation/NzBlXxF3">variance annotation</a>, in contrast with the <i>definition-site</i> variance annotations found in <a href="/facts/C_Sharp_/UC2gxeyb">C#</a> and <a href="/facts/Scala_/ebL8o6AK">Scala</a>. </p>