Quick Answer: What Happens If You Don’T Declare A Default Constructor?

How many default constructors can a class have?

one default constructorA class can only have one default constructor..

Why super is used 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.

Is default constructor necessary?

Java doesn’t require a constructor when we create a class. … The compiler automatically provides a public no-argument constructor for any class without constructors. This is called the default constructor. If we do explicitly declare a constructor of any form, then this automatic insertion by the compiler won’t occur.

What is the drawback of default constructor?

The drawback of a default constructor is that every instance of the class will be initialized to the same values and it is not possible to initialize each instance of the class to different values. The default constructor initializes: All numeric fields in the class to zero. All string and object fields to null.

What happens if a constructor is not defined?

in java, if a class does not define a constructor, compiler will insert a default one for the class, which is argument-less. if a constructor is defined, e.g. super(string s), compiler will not insert the default argument-less one.

Can we inherit a constructor?

No, constructors cannot be inherited in Java. In inheritance sub class inherits the members of a super class except constructors. In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.

Can we declare constructor as 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.

What is the purpose of a default constructor?

If not Java compiler provides a no-argument, default constructor on your behalf. This is a constructor initializes the variables of the class with their respective default values (i.e. null for objects, 0.0 for float and double, false for boolean, 0 for byte, short, int and, long).

Is it possible to overload a default constructor?

A default constructor cannot be overloaded in the same class. This is because once a constructor is defined in a class, the compiler will not create the default constructor. Thus, an attempt to overload the default constructor will effectively remove it from the class. The constructor must not use a different name.

Can a struct have a constructor C#?

Constructors in Structure A struct cannot contain a parameterless constructor. It can only contain parameterized constructors or a static constructor.

Is it possible to inherit constructors of a parent class?

Constructor is a block of code that allows you to create an object of class and has same name as class with no explicit return type. … A parent class constructor is not inherited in child class and this is why super() is added automatically in child class constructor if there is no explicit call to super or this.

When you write your own constructor the default constructor is no longer available?

The default constructor is still available when you add your own constructor. The default constructor can accept arguments. You must write at least one constructor in your class.

What is default arguments give example?

Default arguments are overwritten when calling function provides values for them. For example, calling of function sum(10, 15, 25, 30) overwrites the value of z and w to 25 and 30 respectively.

Can a constructor be empty?

Empty constructor just gives you an instance of that object. … If you want to make sure that any instance created is always valid and any member variables are always initialized,then you would define the constructor which initializes all the required member variables.

Can constructor be overloaded?

Yes! Java supports constructor overloading. In constructor loading, we create multiple constructors with the same name but with different parameters types or with different no of parameters.

Can we declare constructor as static?

No, we cannot define a static constructor in Java, If we are trying to define a constructor with the static keyword a compile-time error will occur. In general, static means class level. A constructor will be used to assign initial values for the instance variables.

Can we have a constructor with all default arguments?

Like all functions, a constructor can have default arguments. They are used to initialize member objects. … Note that if a constructor has any arguments that do not have default values, it is not a default constructor. The following example defines a class with one constructor and two default constructors.

Can a class have two different no args constructors?

Can a class have two different no-args constructors? No. Constructors must have different numbers or types of parameters.

Can we have parameterized constructor without default constructor?

If there is any one parametrized Constructor present in a class, Default Constructor will not be added at Compile time. So if your program has any constructor containing parameters and no default constructor is specified then you will not be able to create object of that class using Default constructor.

Which constructor is called first in C#?

Base ConstructorBase Constructor gets called first. The Exception Constructor will be called, then your Child class constructor will be called. Base Constructor is called first. But the initializer of fields in derived class is called first.

How many arguments does a default constructor have?

There are two type of constructor in Java: No-argument constructor: A constructor that has no parameter is known as default constructor. If we don’t define a constructor in a class, then compiler creates default constructor(with no arguments) for the class.