Java. util. HashMap – why does HashMap extend abstractmap and implement it?
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Java
See English answers > Why do many collection classes in Java extend the abstract class and implement the interface as well? 8
Solution
This is superfluous. I suspect it's for "file" reasons HashMap implements map, which you can rely on The fact that it extends abstractmap can be said to be just an implementation detail (although future versions of HashMap will not extend abstractmap, because there may be some code to assign HashMap to abstractmap.)
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