CODEWITHSUNDEEP
javaelementtreemaptreeset
Camille
Camille

Reputation: 43

TreeMap with as its value a TreeSet, how to remove element from this TreeSet?

I have a TreeMap, where the values are TreeSet. Now I need to loop through the keys, and for each element of the TreeSet I have to delete that element (then continue to do something) and then delete the second element of that TreeSet etc.

I tried:

for (Integer w : adjacencyList.get(keyNow)){        
    adjacencyList.get(keyNow).remove(w);
}

this doesn't work, could somebody please help?

Upvotes: 2

Views: 220

Answers (2)

Peter Lawrey
Peter Lawrey

Reputation: 533550

Similar to @Eran's answer but I would write it like this.

Set<Integer> ints = adjacencyList.get(keyNow);
if (ints != null) {
    for (Iterator<Integer> iter = ints.iterator(); iter.hasNext();) {
         Integer w = iter.next();
         // do something with w
         iter.remove();
    }
}

Note: if you don't need to examine each value you can just clear the set.

Set<Integer> ints = adjacencyList.get(keyNow);
if (ints != null)
    ints.clear(); // remove all.

Upvotes: 1

Eran
Eran

Reputation: 393856

Use an explicit iterator :

if (adjacencyList.containsKey(keyNow)) {
    Iterator<Integer> iter = adjacencyList.get(keyNow).iterator();
    while (iter.hasNext()) {
        Integer w = iter.next();
        iter.remove();
    }
}

Upvotes: 3

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