Can we use final keyword before constructor?

declaring constructor as final

In other words, constructors cannot be inherited in Java, therefore, you cannot override constructors. So, writing final before constructors make no sense. Therefore, java does not allow final keyword before a constructor.

Can we use final static keywords to constructor?

When you use a final keyword with a method or constructor it cannot be overridden. But, a constructor in Java cannot be overridden therefore, there is no need of using the final keyword with the constructor. Since you cannot override a constructor you cannot provide body to it if it is made abstract.

Why can't a constructor be final?

The child class inherits all the members of the superclass except the constructors. In other words, constructors cannot be inherited in Java therefore you cannot override constructors. So, writing final before constructors makes no sense. Therefore, java does not allow final keyword before a constructor.

Can we use final keyword before class?

We can declare Java methods as Final Method by adding the Final keyword before the method name. The Method with Final Keyword cannot be overridden in the subclasses. The purpose of the Final Method is to declare methods of how's definition can not be changed by a child or subclass that extends it.

Which keywords is not allowed with constructor?

The static , final and abstract keywords are not meaningful for a constructor because: static members belong to a class, but the constructor is needed to create an object.

Can a Constructor be final in Java ?

Can we declare interface as final?

If you make an interface final, you cannot implement its methods which defies the very purpose of the interfaces. Therefore, you cannot make an interface final in Java. Still if you try to do so, a compile time exception is generated saying “illegal combination of modifiers − interface and final”.

Can we make constructor as static?

Java constructor can not be static

One of the important property of java constructor is that it can not be static. We know static keyword belongs to a class rather than the object of a class. A constructor is called when an object of a class is created, so no use of the static constructor.

Can we initialize final variable in constructor?

A blank final variable can be initialized inside an instance-initializer block or inside the constructor. If you have more than one constructor in your class then it must be initialized in all of them, otherwise, a compile-time error will be thrown.

Can constructor be inherited?

Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass.

Can we override static method?

Overloading is the mechanism of binding the method call with the method body dynamically based on the parameters passed to the method call. Static methods are bonded at compile time using static binding. Therefore, we cannot override static methods in Java.

Can constructors be virtual?

Constructor can not be virtual, because when constructor of a class is executed there is no vtable in the memory, means no virtual pointer defined yet.

Can we write try catch block in constructor?

Like any method can throw exception, a constructor can also throw a exception since it is also a method which is invoked when a object is created. yes we can write a try catch block within a constructor same as we can write in inside a method.

Can we overload constructor?

Constructors can be overloaded in a similar way as function overloading. Overloaded constructors have the same name (name of the class) but the different number of arguments. Depending upon the number and type of arguments passed, the corresponding constructor is called.

Can we use this () and super () in a constructor?

If we include “this()” or “super()” inside the constructor, it must be the first statement inside it. “this()” and “super()” cannot be used inside the same constructor, as both cannot be executed at once (both cannot be the first statement). “this” can be passed as an argument in the method and constructor calls.

Can a main () method be declared final?

Yes, we can declare the main () method as final in Java. The compiler does not throw any error. If we declare any method as final by placing the final keyword then that method becomes the final method.

Can a constructor be synchronized?

Note that constructors cannot be synchronized — using the synchronized keyword with a constructor is a syntax error. Synchronizing constructors doesn't make sense, because only the thread that creates an object should have access to it while it is being constructed.

Can 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.

Can method be declared static?

Static methods

When a method is declared with the static keyword, it is known as the static method. The most common example of a static method is the main( ) method. As discussed above, Any static member can be accessed before any objects of its class are created, and without reference to any object.

Can we achieve abstraction without encapsulation?

The object is the abstract form of the real-world and its details are hidden using encapsulation. Thus encapsulation is required for abstraction.

Can an abstract class be final?

If you declare a class abstract, to use it, you must extend it and if you declare a class final you cannot extend it, since both contradict with each other you cannot declare a class both abstract and final if you do so a compile time error will be generated.

Can we declare final variable without initialization?

Declaring final variable without initialization

If you declare a final variable later on you cannot modify or, assign values to it. Moreover, like instance variables, final variables will not be initialized with default values. Therefore, it is mandatory to initialize final variables once you declare them.

Can a final class be inherited?

If a class is marked as final then no class can inherit any feature from the final class. You cannot extend a final class.

Can we use void with constructor?

Note that the constructor name must match the class name, and it cannot have a return type (like void ). Also note that the constructor is called when the object is created.

Can constructor be overridden?

Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. But, a constructor cannot be overridden. If you try to write a super class's constructor in the sub class compiler treats it as a method and expects a return type and generates a compile time error.

Why constructor have no 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. Its return value (if it actually has one when compiled down to machine code) is opaque to the user - therefore, you can't specify it.