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Nothing happens. The compiler successfully compiles the class. When a class does not have a specific constructor, the compiler places a default no argument construtor in the class and allows you to compile and execute the class.
public class Test {
}
and
public class Test {
public Test(){
}
}
are one and the same.
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Can you declare and define the constructor within class?
Yes, you can declare and define the constructor within a class. A constructor is a special member function of a class that is automatically called when an object of the class is created. It is used to initialize the object's data members. The constructor can be declared and defined within the class definition or can be defined outside the class definition using the scope resolution operator (::).
What is the difference between default constructor and parameterized constructor?
A default constructor is one that has no parameters (C++ also calls constructors with all default parameters a default constructor), while a parameterized constructor is one that has at least one parameter without a default value. Default constructors can be provided by the compiler if no other constructors are defined for that class or any class the class inherits from, while parameterized constructors must always be defined by the developer.
Why you use constructor instead of function?
For every class an empty constructor will be defined automatically by default unless you provide a constructor definition manually. Constructor in a class can be used to initialize variables or perfrom some basic functionallity whenever an object is created.
What is system defined default constructor in java?
System defined constructor or Default constructor is the constructor that the JVM would place in every java class irrespective of whether we code it manually or not. This is to ensure that we do not have compile time issues or instantiation issues even if we miss declaring/coding the constructor specifically. Ex: public class Test { public String getName() { return "Rocky"l } Public static void main(String[] args){ Test obj = new Test(); String name = obj.getName(); } } Here we were able to instantiate the class Test even though we did not declare a no argument constructor. This is the default constructor that gets called when we try to instantiate it.
Why Java always provides a default constructor to class when you use another constructor default constructor remove?
Classes in Java inherit constructors from their parent classes. If you don't explicitly define a parent class, then Object is used, which has only the default empty constructor. That "default" constructor is only there when defined by the parent class, so classes which do not have a no-argument constructor will not allow subclasses to automatically use it. This is implemented this way because of the special nature of constructors. Java could not always provide a default constructor because it could not guarantee that all class members would be properly created or initialized.
What happens if a constructor is defined in class?
Nothing happens. The compiler successfully compiles the class. When a class does not have a specific constructor, the compiler places a default no argument construtor in the class and allows you to compile and execute the class. public class Test { } and public class Test { public Test(){ } } are one and the same.
What happens when no constructor function is declared in a class - in Java?
When any constructor is deffined in your class, the java compiler create a default no argument constructor for you. This constructor only have an invocation to the super class constructor (" super( ) ").
Can you declare and define the constructor within class?
Yes, you can declare and define the constructor within a class. A constructor is a special member function of a class that is automatically called when an object of the class is created. It is used to initialize the object's data members. The constructor can be declared and defined within the class definition or can be defined outside the class definition using the scope resolution operator (::).
A subclass can call constructor method defined by its super class?
True
What happens if a class defines constructor but not one with no argument?
Nothing Happens. Actually such a constructor is called a Default Constructor. Even if we do not write a constructor for a class, Java would automatically place a default constructor inside the class. Ex: Public class Test { public String getName(){ return "Hi"; } } Public class TestEx { public static void main(String[] args){ Test obj = new Test(); System.out.println(obj.getName()); } } Here we were able to instantiate an object of class Test even though we did not define a constructor for that class. This is because Java automatically places a default constructor for the class.
What is the difference between default constructor and parameterized constructor?
A default constructor is one that has no parameters (C++ also calls constructors with all default parameters a default constructor), while a parameterized constructor is one that has at least one parameter without a default value. Default constructors can be provided by the compiler if no other constructors are defined for that class or any class the class inherits from, while parameterized constructors must always be defined by the developer.
How many constructor can be defined in a classin java p rogramming?
how many constructer can be defined in class in overloading of java programming
Why you use constructor instead of function?
For every class an empty constructor will be defined automatically by default unless you provide a constructor definition manually. Constructor in a class can be used to initialize variables or perfrom some basic functionallity whenever an object is created.
What is the advantage of user-defined copy constructor?
What is the advantage of user-defined copy constructor
Can Explain with an example to the default constructor?
The following example shows a Lamborghini class with two constructors: class Lamborghini { Lamborghini() { } Lamborghini(String name) { } } Will the compiler put in a default constructor for the class above? "No!" What about for the following variation of the class? class Lamborghini { Lamborghini(String name) { } } Now will the compiler insert a default constructor? "No Again!" What about this class? class Lamborghini { } Now we're talking. The compiler will generate a default constructor for the preceding class, because the class doesn't have any constructors defined. OK, what about this one below? class Lamborghini { void Lamborghini() { } } You might be tempted to say that, the compiler won't create one, since there already is a constructor in the Lamborghini class? Take another look at the Lamborghini class. What's wrong with the Lamborghini() constructor? It isn't a constructor at all! It's simply a method that happens to have the same name as the class. Remember, the return type is a dead straight way to tell us that we're looking at a method, and not a constructor. So, here again the compiler will put the default no-arg constructor in the class.
Using default constructor in inheritance and in what reason it throws error?
The compiler places a default no-arg constructor in any java class that does not have an explicit constructor coded into it. for ex: public class Car { ... ... //lots of code but no constructor } In the above case, the compiler will place the below constructor into the code: public Car() { super(); } But, if you have a constructor in your class that takes arguments then the compiler will not put the default constructor. Ex: public class Car { public Car(String name){ ... } ... //lots of code } Above, we have a Car constructor that takes a string name as argument. so, the compiler wont put the default constructor in the code. now, if you try to do: Car obj = new Car(); you will get an error because this constructor is not defined.
What is system defined default constructor in java?
System defined constructor or Default constructor is the constructor that the JVM would place in every java class irrespective of whether we code it manually or not. This is to ensure that we do not have compile time issues or instantiation issues even if we miss declaring/coding the constructor specifically. Ex: public class Test { public String getName() { return "Rocky"l } Public static void main(String[] args){ Test obj = new Test(); String name = obj.getName(); } } Here we were able to instantiate the class Test even though we did not declare a no argument constructor. This is the default constructor that gets called when we try to instantiate it.
