return-type

Return different type of data from a method in java?

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I create various return types using enum. It doesn’t defined automatically. That implementation look like factory pattern. public enum SmartReturn { IntegerType, DoubleType; @SuppressWarnings(“unchecked”) public <T> T comeback(String value) { switch (this) { case IntegerType: return (T) Integer.valueOf(value); case DoubleType: return (T) Double.valueOf(value); default: return null; } } } Unit Test: public class MultipleReturnTypeTest { … Read more

Can a C# method return a method?

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The Types you are looking for are Action<> or Func<>. The generic parameters on both types determine the type signature of the method. If your method has no return value use Action. If it has a return value use Func whereby the last generic parameter is the return type. For example: public void DoSomething() // … Read more

Why do constructors in java not have a return type? [duplicate]

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Constructor is internally a nonstatic method with name <init> and void return type. It does not return anything. Internally first object is allocated and then its constructor is called. Object is not allocated with constructor itself. In other words the syntax new Object() not only calls the constructor but also creates new object and after … Read more

Unexpected implicit resolution based on inference from return type

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1) After rewriting your code as follows: case class Monoid[A](m0: A) // We only care about the zero here implicit def s[T] : Monoid[Set[T]] = Monoid(Set.empty[T]) implicit def l[T] : Monoid[List[T]] = Monoid(List.empty[T]) def mzero[A]()(implicit m: Monoid[A]) : A = m.m0 val zero = mzero[List[Int]]() val zero2: List[Int] = mzero() then becomes clearly why that … Read more

Return multiple values from a Java method: why no n-tuple objects?

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I assume the OP means “Why does Java not support n-tuple objects?”. Python, Haskell, Lisp, ML etc have heterogeneous n-tuple capabilities. Also often times the ability to apparently return multiple objects in a language is syntactical sugar (ie in python return ‘a’,’b’). The reason of course is language design and consistency. Java prefers being very … Read more

Simplest way to determine return type of function

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You can leverage std::function here which will give you an alias for the functions return type. This does require C++17 support, since it relies on class template argument deduction, but it will work with any callable type: using ReturnTypeOfFoo = decltype(std::function{foo})::result_type; We can make this a little more generic like template<typename Callable> using return_type_of_t = … Read more

Should I use Unit or leave out the return type for my scala method?

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Implicit Unit return type: def f() {println(“ABC”)} Explicit Unit return type: def g(): Unit = {println(“ABC”)} Return type inferred from the last method expression, still Unit because this is the type of println, but confusing: def h() = println(“ABC”) All the methods above are equivalent. I would prefer f() because the lack of = operator … Read more

Void as return type

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Edit: A new separate RFC for a void return type has been published, has passed the vote, and was implemented in PHP 7.1. There is now a void return type in PHP. 🙂 Original Post: Taken from wiki.php.net: Future Work Ideas for future work which are out of the scope of this RFC include: Allow … Read more

What if I write return statement in constructor?

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Yes, using return statements in constructors is perfectly standard. Constructors are functions that do not return a value. The family of functions that do not return a value consists of: void functions, constructors and destructors. It is stated in 6.6.3/2 in the C++ standard. The very same 6.6.3/2 states that it is illegal to use … Read more