trouble using Map/HashMap 1

[sm43]

Hi,
If the Map class takes Object as parameters for all its methods, how can I put objects belonging to any other type into the map. For example, if I want to do:

Map a = new HashMap() ;

long id ;
String bookname ;

a.put(id,bookname) ;


It doesn't work..I get a compile error on the a.put line saying the parameter's types are wrong.. If I try casting the parameters to (Object) like

a.put((Object) id, (Object) bookname) ;

I get the error that the types cannot be casted into Object. I'm confused. All classes inherit from Object so why does the cast generate compile error. How do I accomplish the task above? If this is not it, what is the workaround? I thought Maps were so you could use them with any types..


Thanks.

Saad

 

[varocho]

Try creating an Integer object out of 'id' first then pass this object and the 'bookname' String to the 'a.put()' function call.

 

[sm43]

Thank you very much. Yes that's exactly what I did. Created a Long object from the long value & passed it to
put(). All classes inherit from Object, but the primitive types don't.


Thanks.

Saad