com.sun.javafx.collections.UnmodifiableListSet Maven / Gradle / Ivy
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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package com.sun.javafx.collections;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.List;
/**
* A special unmodifiable implementation of Set which wraps a List.
* It does not check for uniqueness! There are
* several places in our implementation (Node.lookupAll and
* ObservableSetWrapper are two such places) where we want to use
* a List for speed of insertion and will be in a position to ensure
* that the List is unique without having the overhead of hashing,
* but want to present an unmodifiable Set in the public API.
*/
public final class UnmodifiableListSet extends AbstractSet {
private List backingList;
public UnmodifiableListSet(List backingList) {
if (backingList == null) throw new NullPointerException();
this.backingList = backingList;
}
/**
* Required implementation that returns an iterator. Note that I
* don't just return backingList.iterator() because doing so would
* open up a whole through which developers could remove items from
* this supposedly unmodifiable set. So the iterator is wrapped
* such that it throws an exception on remove.
*/
@Override public Iterator iterator() {
final Iterator itr = backingList.iterator();
return new Iterator() {
@Override public boolean hasNext() {
return itr.hasNext();
}
@Override public E next() {
return itr.next();
}
@Override public void remove() {
throw new UnsupportedOperationException();
}
};
}
@Override public int size() {
return backingList.size();
}
}