Core Java 面试题与答案
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问题 116. Does Java have multiple inheritance?
Java does not support multiple inheritence directly but it does thru the concept of interfaces.
We can make a class implement a number of interfaces if we want to achieve multiple inheritence type of functionality of C++.
问题 117. What is the super class of Hashtable?
问题 118. What are some alternatives to inheritance?
Delegation is an alternative to inheritance. Delegation means that you include an instance of another class as an instance variable, and forward messages to the instance. It is often safer than inheritance because it forces you to think about each message you forward, because the instance is of a known class, rather than a new class, and because it doesn't force you to accept all the methods of the super class: you can provide only the methods that really make sense. On the other hand, it makes you write more code, and it is harder to re-use (because it is not a subclass).
问题 119. Is a class a subclass of itself?
A class is a subclass of itself.
问题 120. How are this() and super() used with constructors?
this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.
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用户评价最有帮助的内容：
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