A parameterized constructor is one that takes multiple arguments/parameters as input. Ex: let us say we want to create multiple constructor for a class Test
Public class Test {
Public Test() {
//code
}
Public Test(int vals) {
//code
}
Public Test(String val) {
//code
}
}
Parameterised constructors accept arguments while non parameterised constructors do not. Example : class A { A(){ // non parameterised ... } A(int b){ // parameterised ... } }
Every class, including abstract classes, MUST have a constructor. But just because a class must have one, doesn't mean the programmer has to type it. A constructor looks like this: class Car { Car() { } // The constructor for the Car class } You notice anything missing in the declaration above? There's no return type! Two key points to remember about constructors are that they have no return type and their names must exactly match the class name. The above car() is the non-parameterised or no-arg constructor for the class.
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.
An empty constructor takes no arguments and calls the default constructor
An implicit constructor call will always call the default constructor, whereas explicit constructor calls allow to chose the best constructor and passing of arguments into the constructor.
there are two types of constructure. 1. Default constructure 2. Parameterised constructure
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
yes we can call constructor
Constructor is used to do something (written in constructor) immediately after object creation.
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
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( ) ").
Java has 2 types of constructors based on parameters passed:Default or parameter-less constructor: A constructor which does not accept any arguments.Parametrized constructor: A constructor which accepts one or more arguments.Similarly based on Access modifier also we have:Public constructor - Class can be instantiated by anyonePrivate constructor - Class cannot be instantiated by anyoneProtected constructor - Class can be instantiated only by sub classes