General Java Questions I

implement one or more interfaces. Interfaces are Java s way to support multiple

inheritance.

 Q: There are two interfaces which have a common methods action() in them and

class implements both of them...

There are two interfaces which have a common methods action() in them and class

implements both of them, override them and then in a test class simply call action. 

Which will be called?

And next: is there any way of resolving this conflict like in c++ we can

first::action();

second::action();

is something same is there in java?

Answer: 

1. Neither. The compiler will refuse to compile Hello because it has two methods with

the same name and parameter list.

2. In Java, one would usually deal with this sort of situation by implementing the

interfaces in Hello s inner classes, rather than the Hello itself. You can have two inner

classes, each implementing one of the interfaces, and each with an action method

that just calls a uniquely named method in the surrounding Hello object.

Patricia

 Does anyone know how could I get the size of an Enumeration object? The API

for Enumeration only contains getNext() and next().

Answer 1: You can t. Theoretically, some classes that implement Enumeration may

also provide some way to get a size, but you d have to know about the more specific

run time type and cast to it... and none of the standard java.util Collections classes

nor Vector or such provide these methods in their Enumeration implementations.

Answer2:  

you can make your own class like this:

import java.util.*;

public class MyEnumeration{

   int size;

   int index = 0;

   Enumeration e;

   public MyEnumeration(Vector v){

      size = v.size();

      e = v.elements();

      index = 0;

   }

   public boolean hasMoreElements(){

      return e.hasMoreElements();

   }

file:///F|/a_jsite/350_tips/general_java I.htm (8 of 33) [2001 07 08 11:24:51]