I have 3 different TreeSet objects in my application, all of which store the same class of object.
However, at any one point of time, a single object may exist in only one of the TreeSets.
So, if I queried each TreeSet using contains() for a particular object it should exist in only one of them.
Is there an easy way to add this kind of logic to my TreeSet easily? Obviously I can perform the above contains() check myself after each operation but just wondering if there are better ways?
Thanks
You can keep a map that maps objects to the TreeSet to which they currently belong. If an object has no entry, it can be added to a TreeSet; otherwise it must be removed from the mapped TreeSet before it assigned to a new one.
EDIT:
Per your request, here's a code snippet for how this might be done:
Map<MyObject, TreeSet<MyObject>> map = new HashMap<MyObject, TreeSet<MyObject>>();
void addToSet(MyObject obj, TreeSet<MyObject> set) {
TreeSet<MyObject> otherSet = map.get(obj);
if (otherSet != null) {
otherSet.remove(obj);
}
set.add(obj);
map.put(obj, set);
}
void removeFromSet(MyObject obj, TreeSet<MyObject> set) {
set.remove(obj);
map.remove(obj);
}
maybe something like:
import java.util.*;
class Sets {
Sets(TreeSet<Integer> set1, TreeSet<Integer> set2, TreeSet<Integer> set3) {
this.set1 = set1;
this.set2 = set2;
this.set3 = set3;
}
boolean add(TreeSet<Integer> set, Integer i) {
if (set == set1) {
if (set2.contains(i)) {
set2.remove(i);
return set.add(i);
} else if (set3.contains(i)) {
set3.remove(i);
return set.add(i);
} else return set.add(i);
}
else if (set == set2) {
if (set1.contains(i)) {
set1.remove(i);
return set.add(i);
} else if (set3.contains(i)) {
set3.remove(i);
return set.add(i);
} else return set.add(i);
}
else if (set == set3) {
if (set1.contains(i)) {
set1.remove(i);
return set.add(i);
} else if (set2.contains(i)) {
set2.remove(i);
return set.add(i);
} else return set.add(i);
}
return false;
}
final TreeSet<Integer> set1, set2, set3;
}
public class Main {
public static void main(String[] args) {
TreeSet<Integer> set1 = new TreeSet<Integer>();
set1.add(1);
TreeSet<Integer> set2 = new TreeSet<Integer>();
set2.add(2);
TreeSet<Integer> set3 = new TreeSet<Integer>();
Sets sets = new Sets(set1, set2, set3);
System.out.println(set1);
System.out.println(set2);
System.out.println(set3);
sets.add(set3,1);
sets.add(set3,2);
sets.add(set3,3);
System.out.println(set1);
System.out.println(set2);
System.out.println(set3);
}
}
