This week's book giveaway is in the Jobs Discussion forum.
We're giving away four copies of Java Interview Guide and have Anthony DePalma on-line!
See this thread for details.
The moose likes Java in General and the fly likes org.apache.collections removeAll Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login

Win a copy of Java Interview Guide this week in the Jobs Discussion forum!
JavaRanch » Java Forums » Java » Java in General
Bookmark "org.apache.collections removeAll" Watch "org.apache.collections removeAll" New topic

org.apache.collections removeAll

Miran Cvenkel
Ranch Hand

Joined: Nov 23, 2010
Posts: 169

a = java.util.List containing [1]
b = java.util.HashSet containing [1,2]

cleared comes out as [1]
I belive it should be []

What is that I dont see ?

Searchable nature photo gallery:
Jesper de Jong
Java Cowboy
Saloon Keeper

Joined: Aug 16, 2005
Posts: 15094

Can you show us some more of the code; specifically, how are a and b declared and filled with data?

This gives me a hint: cleared is a Collection<java.util.List>. So a and b are also collections of lists? Which means, a is a List that contains a List that contains an integer 1, and b is a HashSet that contains a List that contains the integers 1 and 2? If that's the case, then your output is not surprising. The removeAll method is going to try to remove the List [1,2] from a, but since a does not contain a List [1,2], it's not going to remove anything.

Java Beginners FAQ - JavaRanch SCJP FAQ - The Java Tutorial - Java SE 8 API documentation
Miran Cvenkel
Ranch Hand

Joined: Nov 23, 2010
Posts: 169
Hmm, yes, possible. Thanks.

Yeah could post the code, but it become ugly as hell , me spinning around this (-:,%20java.util.Collection%29

removeAll(java.util.Collection collection, java.util.Collection remove)
Removes the elements in remove from collection.

A bit confusing.

Figured that substract does what I want.
But will test that a bit more.
I agree. Here's the link:
subject: org.apache.collections removeAll
It's not a secret anymore!