Factory method

Factory method:

Factory method is a java method return is the same class object.

Factory method is an idea provided by ‘factory method design pattern”.

Ex code :-

class A

{

                private A()

                {

                }

                void m1()

                {

                                System.out.println("m1-A");

                }

                static A getRef()  //Factory Method

                {

                                A a=new A();

                                return a;

                }

}

class Test

{

                public static void main(String[] args)

                {

                                A a=A.getRef();

                                a.m1();

                }

}

Output:-

m1-A

There are two types of factory method:

1.       Static factory method

2.       Instance factory method

1.        Static factory method :

It is a static method return the same class object

Ex:-

        Class c=Class.forName("A");

        NumberFormate nf=NumberFormate.getInstance(--);

        DateFormat df=DateFormat.getDateInstance(--);

        ResourcBundle rb=ResourcBundle.getBundle(--);

2.       Instance factory method :

If any instance method, return the same class object then that instance method is called as “Instance Factory method”.

Ex:-

Majority of string class method are instance factory methods.

Ex:-

class Test

{

        public static void main(String[] args)

        {

                        String str="Sai Software Solution";

                        String str1=str.concat("Hyderabad");

                        String str2=str.trim();

                        String str3=str.substring(4,14);

                        String str4=str.toUpperCase();

                        //----

                        //----

                        //----

                        System.out.println(str);

                        System.out.println(str1);

                        System.out.println(str2);

                        System.out.println(str3);

                        System.out.println(str4);

        }

}

Output:-

Sai Software Solution

Sai Software SolutionHyderabad

Sai Software Solution

Software S

SAI SOFTWARE SOLUTION

Note:-

Design pattern is a system, it will provide problem definition and solution for that problem in order to solve design problem which are getting in java application.