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java 1.5 generic and autocasting

Steve Jiang
Ranch Hand

Joined: May 17, 2004
Posts: 107
From http://java.sun.com/j2se/1.5.0/docs/guide/collections/changes5.html,

Generics - adds compile-time type safety to the collections framework and eliminates the need to cast when reading elements from collections.
Enhanced for loop - eliminates the need for explicit iterators when interating over collections.
Autoboxing/unboxing - automatically converts primitives (such as int) to wrapper classes (such as Integer) when inserting them into collections, and converts wrapper class instances to primitives when reading from collections.



I think the following code should work, but the compiler complains " Incompatbable type for Object and int or Integer" , what is wrong with me for generic and autocasting?

Thanks,



[ January 17, 2008: Message edited by: Steve Jiang ]
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19760
    
  20

You declared the HashMap without generics, so it only knows that it returns Object.

If you change that into HashMap<String, Integer>, or even better Map<String, Integer> it should work.


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