What is the meaning of the question mark in angle brackets? Extend Java lang.Comparable>
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Java
In the App Engine, according to the Javadoc, the gettyperank method has this signature:
public static int getTypeRank(java.lang.Class<? extends java.lang.Comparable> datastoreType)
In the method signature, there is a question mark in angle brackets:
< ;? Extend Java lang.Comparable>
What's the meaning of this?
Solution
？ Basically represents wildcards& LT ;? Extend Java Lang. comparable > means that "any type that extends Java. Lang. comparable (or comparable itself) can be used here"
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