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Generics

 
Ranch Hand
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hi guys,

If you are using generics, you should make sure that :


The only way to invoke that method is to pass Animal list as argument, no subtypes.
Or the other ways are to use the wildcard (extends & super, ?, conditions apply) ... but what about return type?



i saw questions that used generic methods and returned subtype of declared return type from methods.
 
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Hello Rafi,

It will not compile. The compiler slaps us in the face with message something like "Type mismatch: cannot convert from List<Dog> to List<Animal>"


This however compiles and works fine:

Now we declared that this method will return a List of Animals, but now it may also contain Animal subclasses like Dog.
 
Rafi Fareen
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Innar Made wrote:Hello Rafi,

It will not compile. The compiler slaps us in the face with message something like "Type mismatch: cannot convert from List<Dog> to List<Animal>"


This however compiles and works fine:

Now we declared that this method will return a List of Animals, but now it may also contain Animal subclasses like Dog.



thanks bro, i got it ;)
 
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