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;
}
}