Is there any Java open-source comparator for comparing beans by multiple fields for multi-column sorting? Each column can be sorted asceding or descending.
For single-column sorting it can be achieved by using org.apache.commons.beanutils.BeanComparator
together with org.springframework.util.comparator.InvertibleComparator
.
I'm aware that this functionality is quite trivial to write, but what's the benefit from reinventing the wheel, if it was already written and tested?
I wrote this a few months ago.
public abstract class ChainedComparator<T> implements Comparator<T> {
private Comparator<T> next;
@Override
public int compare(T o1, T o2) {
int result = doCompare(o1, o2);
if (result == 0) {
if (getNext() != null) {
return getNext().compare(o1, o2);
}
}
return result;
}
public abstract int doCompare(T o1, T o2);
public Comparator<T> getNext() {
return next;
}
public void setNext(Comparator<T> next) {
this.next = next;
}
}
Just inherit from this class and override the doCompare-Method. Then set a the next comparator in chain with setNext()
. The earlier a comparator appears in this chain, the more "important" it is.
EDIT:
Also see what I found: http://commons.apache.org/collections/api-2.1.1/org/apache/commons/collections/comparators/ComparatorChain.html
This is part of the apache commons collection library, which you can download here
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With