how to use Constructor in java?

Every class must have at least one constructor.

If there is no constructors for your class, the compiler will supply a default constructor(no-arg constructor).

A constructor is used to construct an object.

A constructor looks like a method and is sometimes called a constructor method.

A constructor never returns a value

A constructor always has the same name as the class.

A constructor may have zero argument, in which case it is called a no-argument (or no-arg, for short) constructor.

Constructor arguments can be used to initialize the fields in the object.

The syntax for a constructor is as follows.


constructorName (listOfArguments) {

    [constructor body]


public class MainClass {

  double radius;


  // Class constructor

  MainClass(double theRadius) {

    radius = theRadius;