Can we write method in constructor?

Yes, as mentioned we can call all the members of a class (methods, variables, and constructors) from instance methods or, constructors.

Can you use methods in a constructor?

A constructor can call methods, yes. A method can only call a constructor in the same way anything else can: by creating a new instance. Be aware that if a method constructs a new object of the same type, then calling that method from a constructor may result in an infinite loop...

Can we write constructor in main method?

main() method is the entry point for any program in java. This is the method which is invoked by the JVM to execute the program. Every class including abstract classes has a constructor. Even if you don't declare one explicitly, compiler will add a default constructor.

Can you 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.

Does constructor run before main method?

A static constructor is used to initialize any static data, or to perform a particular action that needs to be performed only once. It is called automatically before the first instance is created or any static members are referenced. So, the static constructor is called before the Main method.

Java Constructor Tutorial - Learn Constructors in Java

Is it bad to call methods in constructor?

You shouldn't: calling instance method in constructor is dangerous because the object is not yet fully initialized (this applies mainly to methods than can be overridden). Also complex processing in constructor is known to have a negative impact on testability.

Is it good practice to call a method in constructor?

Yes, you could do that work in a constructor, though I might consider using a static "Create" method on the Project class instead.

Is it good to call function in constructor?

A C++ constructor calls a virtual function. As a general rule, you should never call virtual functions in constructors or destructors. If you do, those calls will never go to a more derived class than the currently executing constructor or destructor.

Can we return this from a method?

Yes, you can return this in Java i.e. The following statement is valid. return this; When you return "this" from a method the current object will be returned.

Can we call member function in constructor?

Member functions are allocated when class is defined, constructors are invoked only when objects are created. So it shouldn't hurt calling a member function from a constructor !

How do you call a function inside a constructor?

What happens if we call a method in the ctor?

Your answer

You create an instance of B. B() calls superclass constructor - A(), to initialize the superclass members. A() now invokes a non-final method which is overridden in B class, as a part of initialization. Since the instance in the context is of B class, the method load() invoked is of B class.

What happens if we call a method in a static method of the class?

If you try to call a static method via an instance you will get warning as you should avoid it, so you wont get a valid case but yes its logical to allow static call through instance.

What happens if we call a private method in the ctor?

It's ok to call private methods from your constructor to initialize some data that used inside the class. Just be sure that your methods have no "side-effects" like long-time methods that user of your class would probably not expect with just calling your constructor.

Why do we use super in Java?

The super keyword refers to superclass (parent) objects. It is used to call superclass methods, and to access the superclass constructor. The most common use of the super keyword is to eliminate the confusion between superclasses and subclasses that have methods with the same name.

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 static method be overridden?

Static methods are bonded at compile time using static binding. Therefore, we cannot override static methods in Java.

Can we access static variable in non static method?

“Can a non-static method access a static variable or call a static method” is one of the frequently asked questions on static modifier in Java, the answer is, Yes, a non-static method can access a static variable or call a static method in Java.

Is overriding possible in Java?

In Java, method overriding occurs when a subclass (child class) has the same method as the parent class. In other words, method overriding occurs when a subclass provides a particular implementation of a method declared by one of its parent classes.

Can we override constructor in Java?

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.

How do you call a main method from a constructor in Java?

Can we create a method in a constructor in Java?

Yes, as mentioned we can call all the members of a class (methods, variables, and constructors) from instance methods or, constructors.

Can we call virtual method from constructor?

You can call a virtual function in a constructor, but be careful. It may not do what you expect. In a constructor, the virtual call mechanism is disabled because overriding from derived classes hasn't yet happened. Objects are constructed from the base up, “base before derived”.

Can we call virtual function from destructor?

Similarly, it is permissible to call a virtual function from a constructor or destructor of a class that has the final class-virt-specifier, as in this example.

Can we make destructor as private?

Private Destructor in C++ Destructors with the access modifier as private are known as Private Destructors. Whenever we want to prevent the destruction of an object, we can make the destructor private.