can some one explain me this java boolean expression

amolgupta · 05-10-2006, 05:22 AM

(o==null ? e==null : o.equals(e))

o is object.
i need to know thi to undersand collection.contains(object )

here is the link http://java.sun.com/j2se/1.4.2/docs/...a.lang.Object)

spooon · 05-10-2006, 05:51 AM

They mean if "o" and "e" are either both null or are "equal". It's essentially saying "o.equals(e)", except they account for the technicality that if "o" was null then obviously you can't call the ".equals()" method, but for our purposes we still want null references to be considered equal to each other.

Vagrant · 05-10-2006, 11:10 AM

Look up the ternary operator.

amolgupta · 05-11-2006, 02:46 AM

how can i override them the .equals() function in a subclass of object

spooon · 05-11-2006, 04:54 AM

Quote:

Originally Posted by amolgupta

how can i override them the .equals() function in a subclass of object

Just define a method in your class like this:

Code:

public boolean equals(Object obj) {
// blah blah blah
}