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By using the reference super();
When you invoke super(); the JVM knows that you are trying to invoke the constructor from the parent class and calls the super class constructor automatically. In fact, the invocation to super(); is usually the first line of any class constructor. This is done to ensure that all the parent class objects are initialized before the current child class is created.
What else can I help you with?
How constructor called?
You cannot invoke a constructor explicitly. It will get invoked implicitly when you call the new keyword on the class to create an object of the class. Ex: private ClassExample obj = new ClassExample(); here this new keyword usage on the ClassExample class will invoke the constructor of this class and create an object of that class.
When invoking a constructor from subclass its super class's no-arg constructor is always invoked?
Implicitly: (i.e., you do not code for it, but works as if you did)calling the no-argument constructor of the subclass, and there is no explicitly "redirect" codes.Explicitly:a constructor with base() / super() in the implementation, even that invoked constructor required some arguments.C# example: public SubClass(string whatever) : base() {//...}
What is mean constructor in java?
A parameterized constructor in java is just a constructor which take some kind of parameter (variable) when is invoked. For example. class MyClass { //this is a normal constructor public MyClass(){ //do something } //this is a parameterized constructor public MyClass(int var){ //do something } //this is another parameterized constructor public MyClass(String var, Integer var2){ //do something } }
When the constructor is called how many times will it be copied?
constructor is called every times when we create object of class using new keywordand constructor can not be copied (vinayak shendre)
Why we can't use super and this keywords in the same constructor?
because, the super refers to the constructor of the parent class while this refers to the constructor of the current class. Either statements must be the first line in a constructor. So, since we cannot have two first lines in a method we cannot have both keywords in the same constructor.public RandomTest() {super();this();}The above code will never compile. Even if we flip the positions of super and this, we will get the same compilation error.
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( ) ").
How does constructor work?
First line in any constructor has to be either super() or this() not both. If any constructor does not contain either of super() and this(), compiler adds super(). When any constructor is called before excuting the code of the constructor, if it founds this(), it will call another constructor else it will call super() which is the call for the constructor of super class, now again from the super class constructor it will call the super class constructor if available. This is continued until it reaches the top of the class hierarchy. ---- Basically, a constructor is a block of code that gets executed each time a particular instance of a class is created. So, say you've designed a class for working with a database of some sort. When you create an instance of that class, copies of all the variables and functions of that class get attached to the instance-object, and if one of the functions is a constructor function, it will be run as soon as the instance-object is created. This lets you automatically set up conditions for the instance (i.e. establishing connections to different databases or reading data from different tables, or etc.). Depending on the language you're using, classes may or may not automatically call the constructor function of a parent or super class (if such exists, and if you do not provide a constructor for the class in question).
How constructor called?
You cannot invoke a constructor explicitly. It will get invoked implicitly when you call the new keyword on the class to create an object of the class. Ex: private ClassExample obj = new ClassExample(); here this new keyword usage on the ClassExample class will invoke the constructor of this class and create an object of that class.
When invoking a constructor from subclass its super class's no-arg constructor is always invoked?
Implicitly: (i.e., you do not code for it, but works as if you did)calling the no-argument constructor of the subclass, and there is no explicitly "redirect" codes.Explicitly:a constructor with base() / super() in the implementation, even that invoked constructor required some arguments.C# example: public SubClass(string whatever) : base() {//...}
Why am I getting Java unreported exception while compiling my class?
It may be because you are using inheritance and your super class constructor has a throws clause in its declaration. If your super class has a throws clause in its constructor declaration, you must do the same in your child class constructor in order to eliminate this compiler error.
A subclass can call constructor method defined by its super class?
True
What is mean constructor in java?
A parameterized constructor in java is just a constructor which take some kind of parameter (variable) when is invoked. For example. class MyClass { //this is a normal constructor public MyClass(){ //do something } //this is a parameterized constructor public MyClass(int var){ //do something } //this is another parameterized constructor public MyClass(String var, Integer var2){ //do something } }
When the constructor is called how many times will it be copied?
constructor is called every times when we create object of class using new keywordand constructor can not be copied (vinayak shendre)
Why we can't use super and this keywords in the same constructor?
because, the super refers to the constructor of the parent class while this refers to the constructor of the current class. Either statements must be the first line in a constructor. So, since we cannot have two first lines in a method we cannot have both keywords in the same constructor.public RandomTest() {super();this();}The above code will never compile. Even if we flip the positions of super and this, we will get the same compilation error.
What is concession constructor?
Constructors are basically used to evoke methods of a class creating its object..and as far as i know there is no constructor called concession constructor..
Why we use super in java?
The keyword super is used to refer to the parent class instance of the current class. Lets say we have a class class A extends B { ... public void getName(){ } ... } Lets assume the parent class B also has a method getName() Inside class A if you call getName() it would by default call the current class's method. To make the JVM intentionally call the super class method we can use super if we say super.getName() then the parent class instance of the method would be called.
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 (::).
