Core Java perguntas e respostas de entrevista
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Pergunta 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++.
Pergunta 117. What is the super class of Hashtable?
Pergunta 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).
Pergunta 119. Is a class a subclass of itself?
A class is a subclass of itself.
Pergunta 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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Mais uteis segundo os usuarios:
- How could Java classes direct program messages to the system console, but error messages, say to a file?
- What are the differences between an interface and an abstract class?
- Why would you use a synchronized block vs. synchronized method?
- How can you force garbage collection?
- What are the differences between the methods sleep() and wait()?