- What is null constructor?
- Can a constructor be final?
- Can a constructor be private?
- Is constructor inherited?
- Can a constructor return null C#?
- Can we pass null in constructor?
- Is it OK to return null?
- Can we have return type for constructor?
- Can we pass null as argument in Java?
- Why returning NULL is bad?
- Should I return null or throw exception?
- What should I return instead of NULL?
What is null constructor?
In computer programming, a nullary constructor is a constructor that takes no arguments.
Also known as a 0-argument constructor or no-argument constructors..
Can a constructor be final?
No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. … In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.
Can a constructor be private?
Yes, we can declare a constructor as private. If we declare a constructor as private we are not able to create an object of a class. We can use this private constructor in the Singleton Design Pattern.
Is constructor inherited?
A subclass inherits all the members (fields, methods, and nested classes) from its superclass. Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass.
Can a constructor return null C#?
No, you can’t get null from a class constructor ( Thread is a class). … Other than that, a constructor will always either return an object (or initialize a struct), or throw an exception.
Can we pass null in constructor?
Some compilers will issue a warning for this, saying that the code will always throw an NPE. However, this is legal Java code, so a conformant Java compiler cannot call this a compilation error. … Don’t use (Integer) null as the parameter. Pass an int value, or an actual (not null) Integer object.
Is it OK to return null?
Yes, returning NULL is a terrible design, in object-oriented world. In a nutshell, NULL usage leads to: ad-hoc error handling (instead of exceptions)
Can we have return type for constructor?
No, constructor does not have any return type in Java. … 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.
Can we pass null as argument in Java?
You cannot pass the null value as a parameter to a Java scalar type method; Java scalar types are always non-nullable. However, Java object types can accept null values. The values of both variable @I and variable @A are null, since values have not been assigned to them.
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.
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.
What should I return instead of NULL?
you can usually simply return an empty object instead of null , and it will work fine, without special handling. In these cases, there’s usually no need for the caller to explicitly handle the empty case.