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Does every class have a no-argument constructor?
All classes have at least one constructor. If a class does not explicitly declare any, the Java compiler automatically provides a no-argument constructor, called the default constructor.
Can a class constructor have 0 parameters?
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 a zero argument constructor?
A zero parameter (or “no-arg”) constructor is one that requires no arguments. A class can have multiple constructors, each with different arguments. Constructors without arguments are particularly helpful for tools that use reflection to populate an object’s properties.
Why do we need constructor in immutable class?
A constructor is a place to write our object initialization logic because constructor gets called whenever we create an object. So when we want to set our object’s state during object creation only, we need to set it in the constructor and that’s why we need to have an argument constructor in case of an immutable class.
Can an immutable class have a zero argument?
If you really mean no zero argument constructors (including private) and forbid access to static global variables and require immutability, then I claim that your object cannot hold any non-constant data, only behaviour (e.g., strategy pattern, as others mentioned).
When do you call a zero parameter constructor?
A constructor is called when instantiating an object. A zero parameter (or “no-arg”) constructor is one that requires no arguments. A class can have multiple constructors, each with different arguments.
Can a ViewModel have a non zero argument constructor?
Otherwise, if you want to have a non zero argument constructor for your ViewModel class, you may have to create a custom ViewModelFactory class to initialise your ViewModel instance, which will implement ViewModelProvider.Factory interface.