'Set = new HashSet' or 'HashSet = new Hashset'?

Posted by Pureferret on Stack Overflow See other posts from Stack Overflow or by Pureferret
Published on 2012-10-03T09:36:25Z Indexed on 2012/10/03 9:37 UTC
Read the original article Hit count: 420

Filed under:

generics

|

collections

|

constructor

|

initialization

I'm intialising a HashSet like so in my program:

Set<String> namesFilter = new HashSet<String>();

Is this functionally any different if I initilise like so?

HashSet<String> namesFilter = new HashSet<String>();

I've read this about the collections interface, and I understand interfaces (well, except their use here). I've read this excerpt from Effective Java, and I've read this SO question, but I feel none the wiser.

Is there a best practice in Java, and if so, why? My intuition is that it makes casting to a different type of Set easier in my first example. But then again, you'd only be casting to something that was a collection, and you could convert it by re-constructing it.

© Stack Overflow or respective owner

Related posts about generics

Java generics: What is the compiler's issue here?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have the following methods: public <T> T fromJson( Reader jsonData, Class<T> clazz ) { return fromJson( jsonData, (Type)clazz ); } public <T> T fromJson( Reader jsonData, Type clazz ) { ... } The compiler is saying about the first method: type parameters of <T>T… >>> More
Why does NUnit ignore datapoints when using generics in a theory

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm trying to make use of the TheoryAttribute, introduced in NUnit 2.5. Everything works fine as long as the arguments are of a defined type: [Datapoint] public double[,] Array2X2 = new double[,] { { 1, 0 }, { 0, 1 } }; [Theory] public void TestForArbitraryArray(double[,] array) { // ... } It… >>> More
Instantiating generics type in java

as seen on Stack Overflow - Search for 'Stack Overflow'
I would like to create an object of Generics Type in java. Please suggest how can I achieve the same. suppose I have the class declaration as: public class Abc<T> { public static void main(String[] args) { // I want to create an instance of T } } >>> More
.NET converting simple arrays to List Generics

as seen on Stack Overflow - Search for 'Stack Overflow'
This question might seem trivial and also stupid at the first glance, but it is much more than this. I have an array of any type T (T[]) and I want to convert it into a List generic (List<T>). Is there any other way apart from creating a Generic list, traversing the whole array and adding the… >>> More
Instantiating a list of parameterized types, making beter use of Generics and Linq

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm hashing a file with one or more hash algorithms. When I tried to parametrize which hash types I want, it got a lot messier than I was hoping. I think I'm missing a chance to make better use of generics or LINQ. I also don't like that I have to use a Type[] as the parameter instead of limiting… >>> More

Related posts about collections

Creating a custom collections class using System.Collections.CollectionBase

as seen on C# Corner - Search for 'C# Corner'
This article will show you how you can create a class that can behave just like a collection class. >>> More
C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
Once again we consider some of the lesser known classes and keywords of C#. In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T>… >>> More
C#/.NET Fundamentals: Choosing the Right Collection Class

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be… >>> More
Using Tree(Map,Set) in Collections

as seen on Internet.com - Search for 'Internet.com'
To add objects to a Tree(Map, Set), implement the Comparable.compareTo method. >>> More
Using Tree(Map,Set) in Collections

as seen on Internet.com - Search for 'Internet.com'
To add objects to a Tree(Map, Set), implement the Comparable.compareTo method. >>> More