Difference between revisions of "Generics"

Revision as of 23:45, 23 May 2011

Collections and Generics

equals() and hashcode()

Mainly used for storing and retrieving objects from hashed collections.
First object's hashcode is used to figure out which hash bucket the object is in
Then the equals() method is used to compare objects in the same hash bucket.

This means that:

equal objects MUST have the same hashcode
unequal objects can have the same (or different) hashcode (e.g. same bucket but objects are different)
objects having different hashcodes MUST be unequal

@@ Line 1: / Line 1: @@
-OCPJP Java Generics
+'''Collections and Generics'''
-<syntaxhighlight lang="java">
+<u>equals() and hashcode() </u>
-public static void main(String[] args) {
+* Mainly used for storing and retrieving objects from hashed collections.
-       System.out.println("Hello World");
+* First object's hashcode is used to figure out which hash bucket the object is in
-}
+* Then the equals() method is used to compare objects in the same hash bucket.
-</syntaxhighlight>
+This means that:
+* equal objects MUST have the same hashcode
+* unequal objects can have the same (or different) hashcode (e.g. same bucket but objects are different)
+* objects having different hashcodes MUST be unequal
 [[Category:OCPJP]]