范型检查
· One min read
A ClassCastException is thrown if a cast is found at run time to be impermissible.
Some casts result in an error at compile time. Some casts can be proven, at compile time,
always to be correct at run time. For example, it is always correct to convert a value of a
class type to the type of its superclass; such a cast should require no special action at run
time. Finally, some casts cannot be proven to be either always correct or always i
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