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parent class for Java.util.Map

Deepika Saxena
Ranch Hand

Joined: Jul 05, 2009
Posts: 59
Hi,
could any body let me know the parent class of java.util.Map interface? as per my knowledge it is java.lang.Object. Please correct me if i am wrong.
--Deepika
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19670
    
  18

An iterface does not have a parent class. It can have multiple "parent" interfaces, if it extends multiple interfaces.

As for a class that implements Map, you can't tell its parent class without knowing the class. Some classes may have Object as the parent class, implementing Map completely themselves. Others may extend AbstractMap, inheriting some methods from it. Others may even extend an existing Map implementation. An example is java.util.Properties, which extends java.util.Hashtable which in turn extends java.util.Dictionary which in turn extends Object. In this hierarchy, only Hashtable and Properties are Maps.


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Jeanne Boyarsky
internet detective
Marshal

Joined: May 26, 2003
Posts: 30299
    
150

Rob said everything I can think on the topic. Since it sounds like you are new to Java, it's probably also helpful to show you how to find this information yourself.

If you go to the JavaDoc for the Map interface, you can see the declaration is:


By contrast, the one for Hashmap is:


As you can see HashMap extends AbstractMap. And it's easy to find out once you know how!


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