Core Java 面试题与答案
Question: What does the "abstract" keyword mean in front of a method? A class?Answer: Abstract keyword declares either a method or a class.If a method has a abstract keyword in front of it,it is called abstract method.Abstract method hs no body.It has only arguments and return type.Abstract methods act as placeholder methods that are implemented in the subclasses. Abstract classes can't be instantiated.If a class is declared as abstract,no objects of that class can be created.If a class contains any abstract method it must be declared as abstract |
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