aspose file tools*
The moose likes Java in General and the fly likes Hashtable key object should have its Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » Java in General
Bookmark "Hashtable key object should have its "equals" method " Watch "Hashtable key object should have its "equals" method " New topic
Author

Hashtable key object should have its "equals" method

javabird user
Greenhorn

Joined: Aug 16, 2011
Posts: 3
Hi All,

Please tell me why an object which is to be used as a key in hashtable should have equals method overridden..
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 40052
    
  28
. . . and its hashCode method.
The hashCode method is used to decide which "bucket" the key-value pair is put into, and the equals() method is used to disambiguate pairs, in case there is more than one pair in a particular "bucket".If the JavaRanchUser class has an overridden equals() method [and hashCode()], that will print out NUISANCE. If the equals() method is not, however, overridden, the Map will not recognise the two keys as identical, and will return something else, and you will get a printout of "null". If the hashCode method is not overridden, the Map will not even find the correct "bucket".
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Hashtable key object should have its "equals" method