Covariant return type

A covariant return type has been added to Java SE5, and he says that overridden methods in a ubiquitous class can return some type of export of the return type of a base class method

Class Grain () {

Public String Tostinrg () {return "Grain";}

}

Class Wheat extends Grain () {
Public String toString () {return "Wheat";}

}

CALSS Mill () {

Grain process () {return new Grain ();}

}

Class Wheatmill extends Mill () {

Wheat precess () {return new Wheat ();}

}

In older versions of Java, the overridden process () method can only return grain types, although wheat is from grain (subclass)

With the covariant return type, it becomes a legitimate return type.

Covariant return type