equals operator and a graph node

[Monty Hall]

Hello,

Suppose I have an object that's a vertex in a graph. Supppose I have a
vector that contains this vertex. Suppose I use the vector's
contain(Object) method. Does java first compare by memory reference ? Or
does it do a "deep" equals?

Monty.

 

[Thomas Hawtin]

Suppose I have an object that's a vertex in a graph. Supppose I have a
vector that contains this vertex. Suppose I use the vector's
contain(Object) method. Does java first compare by memory reference ? Or
does it do a "deep" equals?

What does the documentation say?

http://download.java.net/jdk6/docs/api/java/util/Collection.html#contains(java.lang.Object)

Tom Hawtin

 

[Chris Uppal]

Suppose I use the vector's
contain(Object) method. Does java first compare by memory reference ? Or
does it do a "deep" equals?

It uses the object's equals() method which by default is the same as comparing
by ==, but may be overridden to do a more meaningful comparison. So the answer
is that it depends on the objects in question.

Incidentally, this is specified in the JavaDoc for java.util.Vector.contains(),
though I admit it doesn't exactly jump out at you when you read it.

-- chris