Question: Can You Return Nothing In Java?

What is the difference between Getch and return 0?

2 Answers.

return 0 means you are returning a integer which means at the accepting end the value gotten is 0.

In case of getch(), it hold the display of the console till you press enter..

Can a constructor have a return value?

No, constructor does not return any value. While declaring a constructor you will not have anything like return type. In general, Constructor is implicitly called at the time of instantiation.

How do I return nothing in C++?

You can use the return keyword with nothing only in functions that have a return type of void . You can use the return keyword with NULL in any function that has a pointer (not reference) type as its return type.

Can a function return nothing?

Functions without a return statement known as void functions return None from the function. To return a value other than None, you need to use a return statement in the functions; and such functions are called fruitful functions.

What should I return instead of NULL?

Instead of returning null, or some odd value, return a Special Case that has the same interface as what the caller expects….Return an object of class Customer if the query is successful,Return null if the query does not find any customer.Throw an exception if it is not possible to connect to the database.

What is the difference between return 0 and return 1?

So when you return 1, you are basically returning True as the final value of the function while return 0 is basically returning False as the final value of the function.

Why return is used in Java?

A return statement causes the program control to transfer back to the caller of a method. Every method in Java is declared with a return type and it is mandatory for all java methods. A return type may be a primitive type like int, float, double, a reference type or void type(returns nothing).

Why constructor has no return type not void?

Constructor is internally a nonstatic method with name and void return type. It does not return anything. … 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 calling the constructor returns it.

What does None mean in Python?

Definition and Usage The None keyword is used to define a null value, or no value at all. None is not the same as 0, False, or an empty string. None is a datatype of its own (NoneType) and only None can be None.

What does return 0 do in Java?

It is a keyword which is used to return some value, so it does not need any declaration.It needs only return keyword with value or variables. 4. Generally, return 0 is used to return exit code to the operating system. If we want to explicitly specify an exit code to the operating system, we have to use System.

Is it good to return null in Java?

It’s fine to return null if doing so is meaningful in some way: public String getEmployeeName(int id){ ..} In a case like this it’s meaningful to return null if the id doesn’t correspond to an existing entity, as it allows you to distinguish the case where no match was found from a legitimate error.

Should I return null or throw exception?

Only throw an exception if it is truly an error. If it is expected behavior for the object to not exist, return the null. Otherwise it is a matter of preference. As a general rule, if the method should always return an object, then go with the exception.

Does not have a return type?

Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. Mostly it is used to instantiate the instance variables of a class. If the programmer doesn’t write a constructor the compiler writes a constructors on his behalf.

Why returning NULL is bad?

Return a Null Object Perhaps the method can’t identify the user because the user is anonymous, and not being able to find the user is an expected condition. We shouldn’t handle an expected condition using exceptions. Another option is to use null to represent an unknown user, but returning null is lazy.

Why does constructor doesn’t have a return type?

So the reason the constructor doesn’t return a value is because it’s not called directly by your code, it’s called by the memory allocation and object initialization code in the runtime. … The whole purpose of constructor is to initialize the current state of the object by setting the initial values.

Can optional be Null Java?

In Java 8 you can return an Optional instead of a null . Java 8 documentation says that an Optional is “A container object which may or may not contain a non-null value.

Can optional return null?

5 Answers. An Optional always contains a non-null value or is empty, yes, but you don’t have an Optional, you have a reference of type Optional pointing to null. … Optional isn’t magic, it’s an object like any other, and the Optional reference itself can be null.

How does a function return a value in Python?

A return statement is used to end the execution of the function call and “returns” the result (value of the expression following the return keyword) to the caller. The statements after the return statements are not executed. If the return statement is without any expression, then the special value None is returned.

How do you return nothing in a function?

To literally return ‘nothing’ use pass , which basically returns the value None if put in a function(Functions must return a value, so why not ‘nothing’). You can do this explicitly and return None yourself though.

How do you stop returning null in Java?

10 Tips to Handle Null EffectivelyDon’t Overcomplicate Things. … Use Objects Methods as Stream Predicates. … Never Pass Null as an Argument. … Validate Public API Arguments. … Leverage Optional. … Return Empty Collections Instead of Null. … Optional Ain’t for Fields. … Use Exceptions Over Nulls.More items…•

Should I use null or empty string?

NULL means absence of value (i.e. there is no value), while empty string means there is a string value of zero length. … If the user is able to choose not to provide the gender data, you should save that as NULL (i.e. user did not provide the value) and not empty string (since there is no gender with value ”).