In Java, Can an object have several different classes ?
If yes , how should Inheritance and Interface influence to it?
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1I'm not sure I understand your second question. Can you elaborate on it? Also, is this a homework question?templatetypedef– templatetypedef2011-03-21 03:19:19 +00:00Commented Mar 21, 2011 at 3:19
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download.oracle.com/javase/tutorial/java/IandI/index.htmlMohamed Saligh– Mohamed Saligh2011-03-21 03:22:51 +00:00Commented Mar 21, 2011 at 3:22
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2 Answers
It's not a very well-posed question. Any object can be of one and only one class (ignoring the non-object primitives like int.) On the other hand, a class may have an arbitrary number of superclasses, so your class can match the "is a" relationship of an artitrary number of other classes.
On the interface question, all an interface brings in is a "contract" -- you're making a promise to implement certain methods or have certain properties. This is somewhat similar to multiple inheritance but not really multiple inheritance. Again, implementing an interface means the class has another "is a" property, but it doesn't mean it's fully bringing in the other classes.
1 Comment
corsiKa
+1 for a thorough yet concise answer. Java's "Simple white paper" has this to say about multiple inheritance: "Multiple inheritance--and all the problems it generates--was discarded from Java. The desirable features of multiple inheritance are provided by interfaces."
Yes
class A{}
class B extends A{}
void foo()
{
B b = ...; // here object b is of type B and A(by inheritance)
}
