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Is it necessary that a constructor must have a parameter?
No-argument constructor: A constructor that has no parameter is known as the default constructor. If we don’t define a constructor in a class, then the compiler creates default constructor(with no arguments) for the class. Default constructor provides the default values to the object like 0, null, etc.
What is the difference between a constructor with parameter and without parameter?
The constructor with no parameters is default, you can use it to create an object without any further specification, using a parameter you can specify a name or something else during the creation of the object.
What is the purpose of no parameter constructor?
4 Answers. (a)The no-arg constructor you are referring to is a explicitly defined substitute to the “default constructor”. If the programmer doesn’t explicitly define a constructor,then the compiler(javac) automatically defines a default constructor as ClassName(){} .
Can you write a constructor without parameters in Java?
You don’t have a constructor without parameters, so you can’t write new student(). Note that if you don’t write any constructors at all, the compiler will automatically make a constructor for you, without parameters, but as soon as you write one constructor, this doesn’t happen.
Which is better single constructor or other constructor?
Considering the only thing you’re doing in the constructor is simple assignment, the single constructor solution may be a better choice in your case. The other constructor provides no extra functionality and it’s clear from the design of the constructor with two parameters that the second argument does not need to be supplied.
When do you need to define a constructor in a class?
When no constructors are defined in a class then there is a default constructor (without any parameters) already. In which case you don’t need to define it. But if you have any constructor with some parameters, then you need to define the constructor without parameters as well. Its called overloading the constructor.
What happens if you add optional parameters to a constructor?
If you add more required parameters, and the optional ones must come at the end, you’ll break all your current implementations. You can make the old constructor [Obsolete] and inform the users that it’s going to be removed giving them time to migrate to the new implementation without instantly breaking their code.