Consider providing static factory methods insteads of constructors

Question

The normal way for a class to allow a client to obtain an instance is to provide a public contructor. Another way to do that is providing a public static factory method, whi

Answer 1

One of the advantages is you can give the factory methods understandable names. It will help you easy to understand what function's work in your function and easy to maintain your code in the future. Take a look for this example, hope that it will help you.

    public class Contact {

    private Contact(String displayName, String phoneNumber, int contactType){
    //do something
    }

    //then we will have few functon static to get constructor private
    public static createContactUnknow(String phoneNumber){
        return new Contact("","00000000",0);
    }

    public static createContactValid(String displayName, String phoneNumber, int contactType){
        return new Contact(displayName, phoneNumber, contactType);
    }
}

    //then
    Contact myGirlFriend = Contact.createContactValid("xxxx","000000",1);
    Contact unknowFriend = Contact.createContactUnknow("45454545");