Calling Level of method

Question

In object oriented based programming language like java we can call a method of object by using objectName.methodName() -

aStudent.getName().equals(anotherStudent.getName());

Here to achieve the equals() method I have to use two dots (.). In some case there might be more than 2 dots like -

objectName.methodName1().methodName2().methodName3().methodName4()

My question is - Is there any limitation of such level of method calling ?

as long as every method returns an object, which contains at least one method you can call. — Jama Djafarov, Feb 20 '15 at 18:10
Interesting read: http://stackoverflow.com/questions/1103985/method-chaining-why-is-it-a-good-practice-or-not — Bono, Feb 20 '15 at 18:15
This technique is only reasonable if you love NullPointerExceptions. — DwB, Feb 20 '15 at 18:20

score 4 · Answer 1 · answered Feb 20 '15 at 18:22

There is no technical limit, since writing:

result = foo.bar().baz();

is equivalent to writing

bar = foo.bar();
result = bar.baz();

There is, however, often a design limit: if you are accessing the child of a child of a child of ... an object, you might be violating the Law of Demeter (and this article might clear things up further, in case you're interested.)

Jean-François Savard · Accepted Answer · 2015-02-20T19:52:59.697

2

As long as the method return an object, you can call any public method of this object, so no there is no limitation (none that you should matter.. there is always a limit).

Note that the approach may have no limit, but is not recommended at all, as it is harder to read, and harder to validate in one of the object is null.

edited Feb 20 '15 at 19:52

answered Feb 20 '15 at 18:05

Jean-François Savard

20,626
7
49
76

you can chain in Java exactly the same way.. https://en.wikipedia.org/wiki/Method_chaining#Java – Luís Soares Feb 20 '15 at 18:06
That's comparing apples and oranges, though. You can still *chain* calls. It's just different. – Makoto Feb 20 '15 at 18:07
I did not say you can't chain, I said you can't chain like you could in other languages such as javascript. – Jean-François Savard Feb 20 '15 at 18:07
that is true but it was not clear in you original answer – Luís Soares Feb 20 '15 at 18:08

Calling Level of method

2 Answers2