HashSet.addAll doesn't enforce uniqueness?

[Paul Tomblin]

I'm finding the same object twice in my HashSet, and since I'm building
that HashSet using

Set getSelectedContentItems()
{
Set ciSet = new HashSet();
Iterator chIt = children.iterator();
while (chIt.hasNext())
{
TreeNode child = (TreeNode)chIt.next();
ciSet.addAll(child.getSelectedContentItems());
}
ciSet.add(myContentItem);
return ciSet;
}

I'm wondering if somehow addAll is adding things without enforcing the
Set's constraint against duplicate items. I've already checked that the
class "MyContentItem" class has a "public boolean equals(Object other)"
method.

 

[Daniel Dyer]

I'm finding the same object twice in my HashSet, and since I'm building
that HashSet using

Set getSelectedContentItems()
{
Set ciSet = new HashSet();
Iterator chIt = children.iterator();
while (chIt.hasNext())
{
TreeNode child = (TreeNode)chIt.next();
ciSet.addAll(child.getSelectedContentItems());
}
ciSet.add(myContentItem);
return ciSet;
}

I'm wondering if somehow addAll is adding things without enforcing the
Set's constraint against duplicate items. I've already checked that the
class "MyContentItem" class has a "public boolean equals(Object other)"
method.

Does it also over-ride hashCode(), and are the two methods consistent with
each other?

Dan.

 

[Thomas Hawtin]

I'm finding the same object twice in my HashSet, and since I'm building

^^^^

that HashSet using

Set's constraint against duplicate items. I've already checked that the
class "MyContentItem" class has a "public boolean equals(Object other)"
method.

And an @Override public int hashCode()?

Tom Hawtin

 

[Paul Tomblin]

In a previous article, (e-mail address removed) (Paul Tomblin) said:

Set's constraint against duplicate items. I've already checked that the
class "MyContentItem" class has a "public boolean equals(Object other)"
method.

Thomas and Daniel hit the nail on the head - I forgot to override
hashCode. Thanks.