collections – Page 42

make ArrayList Read only

February 24, 2023 by Tarik

Pass the ArrayList into Collections.unmodifiableList(). It returns an unmodifiable view of the specified list. Only use this returned List, and never the original ArrayList.

Determining whether an object is a member of a collection in VBA

February 23, 2023 by Tarik

Isn’t it good enough? Public Function Contains(col As Collection, key As Variant) As Boolean Dim obj As Variant On Error GoTo err Contains = True obj = col(key) Exit Function err: Contains = False End Function

How to sort alphabetically while ignoring case sensitive?

February 22, 2023 by Tarik

Collections.sort(listToSort, String.CASE_INSENSITIVE_ORDER);

Can Java 8 Streams operate on an item in a collection, and then remove it?

February 21, 2023 by Tarik

You can do it like this: set.removeIf(item -> { if (!item.qualify()) return false; item.operate(); return true; }); If item.operate() always returns true you can do it very succinctly. set.removeIf(item -> item.qualify() && item.operate()); However, I don’t like these approaches as it is not immediately clear what is going on. Personally, I would continue to use … Read more

How can I rename a collection in MongoDB?

February 21, 2023 by Tarik

Close. Use db.originalCollectionName.renameCollection(‘newCollectionName’) See http://www.mongodb.org/display/DOCS/renameCollection+Command

Java 8 stream map to list of keys sorted by values

February 21, 2023 by Tarik

You say you want to sort by value, but you don’t have that in your code. Pass a lambda (or method reference) to sorted to tell it how you want to sort. And you want to get the keys; use map to transform entries to keys. List<Type> types = countByType.entrySet().stream() .sorted(Comparator.comparing(Map.Entry::getValue)) .map(Map.Entry::getKey) .collect(Collectors.toList());

Does C# have a way of giving me an immutable Dictionary?

February 20, 2023 by Tarik

No, but a wrapper is rather trivial: public class ReadOnlyDictionary<TKey, TValue> : IDictionary<TKey, TValue> { IDictionary<TKey, TValue> _dict; public ReadOnlyDictionary(IDictionary<TKey, TValue> backingDict) { _dict = backingDict; } public void Add(TKey key, TValue value) { throw new InvalidOperationException(); } public bool ContainsKey(TKey key) { return _dict.ContainsKey(key); } public ICollection<TKey> Keys { get { return _dict.Keys; } … Read more

Best way to remove multiple items matching a predicate from a .NET Dictionary?

February 19, 2023 by Tarik

Here’s an alternate way foreach ( var s in MyCollection.Where(kv => kv.Value.Member == foo).ToList() ) { MyCollection.Remove(s.Key); } Pushing the code into a list directly allows you to avoid the “removing while enumerating” problem. The .ToList() will force the enumeration before the foreach really starts.