There is no such thing as 'the general syntax of a default constructor'. A default constructor is one that is generated by the compiler if you don't specify any constructors at all. Semantically speaking, it is public and takes no arguments, but this is not 'syntax'.
If you don't type a constructor into your class code, a default constructor will be automatically generated by the compiler. The default constructor is ALWAYS a no-arg constructor. (Obviously the compiler has no clue what all arguments you might want for your class. So it takes the safe way out with a no argument constructor) A no-arg constructor is not necessarily the default (i.e., compiler-supplied) constructor, although the default constructor is always a no-arg constructor. The default constructor is the one the compiler provides! While the default constructor is always a no-arg constructor, you're free to put in your own no-arg constructor.
Any constructor that can be invoked without explicitly passing any arguments is a default constructor. Note that there can be only one default constructor so there can only be one constructor where all arguments have default values or one constructor that has no arguments, but not both. A constructor where all arguments have default values is a useful means of combining two or more constructors into a single default constructor, thus reducing verbosity and code duplication.
default constructor is used only when the programmer does not use a constructor to initialize objects. Once the programmer defines a constructor then the default constructor is no longer used
An empty constructor takes no arguments and calls the default constructor
The default constructor is an empty (only call the super constructor) with no parameters constructor inserted by the java compiler when you don't define a constructor in your class. If you write something like this: public class NoConstructorClass{ //no constructor goes here } Then you get something like this: public class NoConstructorClass{ public NoConstructorClass(){ // Default constructor that you didn't write super(); } }
If you don't type a constructor into your class code, a default constructor will be automatically generated by the compiler. The default constructor is ALWAYS a no-arg constructor. (Obviously the compiler has no clue what all arguments you might want for your class. So it takes the safe way out with a no argument constructor) A no-arg constructor is not necessarily the default (i.e., compiler-supplied) constructor, although the default constructor is always a no-arg constructor. The default constructor is the one the compiler provides! While the default constructor is always a no-arg constructor, you're free to put in your own no-arg constructor.
There is no such thing as a default parameterized constructor. The default constructor is always the 'no-arg' constructor and does not take any parameters or arguments as input
Any constructor that can be invoked without explicitly passing any arguments is a default constructor. Note that there can be only one default constructor so there can only be one constructor where all arguments have default values or one constructor that has no arguments, but not both. A constructor where all arguments have default values is a useful means of combining two or more constructors into a single default constructor, thus reducing verbosity and code duplication.
default constructor is used only when the programmer does not use a constructor to initialize objects. Once the programmer defines a constructor then the default constructor is no longer used
No-Arg Constructor
An empty constructor takes no arguments and calls the default constructor
The default constructor is an empty (only call the super constructor) with no parameters constructor inserted by the java compiler when you don't define a constructor in your class. If you write something like this: public class NoConstructorClass{ //no constructor goes here } Then you get something like this: public class NoConstructorClass{ public NoConstructorClass(){ // Default constructor that you didn't write super(); } }
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.
A constructor is a class method which initialises an object of the class at the point of instantiation. Specifically, it initialises the base classes (if any) and the non-static data members (if any). Constructors also play a central role in the resource acquisition is initialisation (RAII) paradigm. Objects which have a natural default value have a default constructor. The default constructor is a constructor that has no arguments or where all arguments have default values. Objects which can be copied have a copy constructor. The copy constructor has just one non-default argument, a const l-value reference of the same type as the class. Objects which can be moved have a move constructor. The move constructor has just one non-default argument, a modifiable r-value reference of the same type as the class. All other constructors that have only one argument of a type other than the class itself are known as conversion constructors. Constructors can also have more than one argument. No specific name is given to these constructors. Other than physical memory constraints, there is no limit to the number of constructors that may be defined for a class.
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.
Default Constructor will be called first . If you override Validate method , then validate method will be called .
Yes, If you don't a default constructor will be created for you.