Can we create object without constructor in Java?
Yes, deserializing an object does not invoke its constructor. Deserialization involves creating objects without invoking a constructor. It’s possible (at least with the Sun/Oracle JDK) to do this programmatically.
Why we use constructor instead of methods in Java?
The purpose of constructor is to initialize the object of a class while the purpose of a method is to perform a task by executing java code. Constructors cannot be abstract, final, static and synchronised while methods can be. Constructors do not have return types while methods do.
What is the difference between constructor and method in Java?
A Constructor is a block of code that initializes a newly created object. A Method is a collection of statements which returns a value upon its execution. A Constructor can be used to initialize an object. A Method consists of Java code to be executed.
Can we create an object of constructor?
When you create an object, you are creating an instance of a class, therefore “instantiating” a class. The new operator requires a single, postfix argument: a call to a constructor. The name of the constructor provides the name of the class to instantiate. The constructor initializes the new object.
When to use factory methods instead of constructors in Java?
The factory creates instances of classes that derive from the baseclass or that implement the interface. A cite from “Effective Java”, 2nd ed., Item 1: Consider static factory methods instead of constructors, p. 5:
Which is better constructor or factory method in OOP?
For everything else a better approach is to use static factory method or in more complex cases a separate factory or builder class. Do minimal work in the constructor. Constructors should not do much work other than to capture the constructor parameters.
Can a complex constructor be called in a static factory?
The book goes as far as to suggest making the Complex (float) constructor private, to force the user to call the static factory method. A concrete example from a CAD/CAM application.
What are the advantages of static factory methods?
Static factory methods advantages: They have names. They are not required to create a new object each time they are invoked. They can return an object of any subtype of their return type. They reduce verbosity of creating parameterized type instances.