This question already has answers here:
What does it mean to "program to an interface"?
(33 answers)
Java - declaring from Interface type instead of Class
(7 answers)
Closed 11 months ago.
Set set= new TreeSet<>();
vs
TreeSet set= new TreeSet<>();
I know we are using the concept of run time polymorphism here, but what is the use of writing this? Is there any advantage to writing one thing over another? both are giving me the correct results. I am learning java right now, help would be great.
Related
This question already has answers here:
How to achieve method chaining in Java?
(4 answers)
Closed 3 years ago.
For example how do I do this?
getServer().getManager().registerNewUser(arguments);
and
getServer().getStats().user(arguments);
Stuff like this, I've tried searching the web but I cant find any tutorials on this,so I'm asking here.
In OOP, in general, this concept is called class composition more on this you can find it here https://en.wikipedia.org/wiki/Object_composition
Also for java and the difference between Composition and inheritance https://www.baeldung.com/java-inheritance-composition
This question already has answers here:
Difference between object and instance
(15 answers)
The difference between Classes, Objects, and Instances
(16 answers)
What is the difference between object and instance?
(10 answers)
Closed 3 years ago.
Is instance and object same thing in OOP or not?
A good explanation Here. But some explanation is so confusing.
I want to know best explanation. Advance thanks .
This question already has answers here:
How come an abstract class "DocumentBuilderFactory" allowed to instantiate new instance
(4 answers)
Constructors vs Factory Methods [closed]
(10 answers)
Closed 4 years ago.
I am doing some Java homework and we are currently studying IO and files in java.
In the directions it asks for us to instantiate a filesystem class. However this doesn't seem possible without using the following syntax. How can I better understand this?
FileSystem fs = FileSystems.getDefault();
Thanks for any help.
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Class or variable not found
(2 answers)
Should Javadoc comments be added to the implementation?
(7 answers)
Closed 5 years ago.
I'm creating the javadoc of my project, but i'm not sure where should i write it.
I have all the javaDoc implemented in my interfaces. And I have classes implementing these interfaces (and not adding extra-methods). So, Is there any command to copy the javadoc from the interfaces to my classes? Or should i Copy-paste from my interfaces to the implementation?
This question already has answers here:
Is there a difference between explicitly putting the type into the diamond operator vs letting java figure it out?
(4 answers)
Closed 5 years ago.
What is purpose of re-specifying the type on the right / constructor side of a Java Collection declaration + instantiation?
For example, how is
List<MyClass> a = new ArrayList<MyClass>();
different / better / worse than
List<MyClass> a = new ArrayList<>();
My understanding is the the second form became legal in Java 7, but I still see a lot of examples in Java 7 and 8 where the first form is used.
It is not worse or different. It is the same.
A new and easy way introduced by compiler to reduce human effort of defining of type.