Implementing Memcache in Java

Do you have a facade[^] in your aplication?

if so it's simple, you would only have to extend the write/read and delete mechanisms.

How to implement a facade into an existing application:
- set up a class "FacadeService". that one is triggered BEFORE your GUI starts.
- FacadeService implements Serializable. the class needs a methode "getInstance()" which gives back a instance of FacadeService.
This is your general entrance point. FacadeService pulls up the rest of the facade (in this example a facade to store Customers in):

import java.io.Serializable;

public class FacadeService implements Serializable {
	private static final long serialVersionUID = 1L;

	private static final FacadeService oFacadeService = new FacadeService();
	
	private final CustomerFacade oCustomerFacade = new CustomerFacade();
	
	public FacadeService(){
		// maybe do something or just leave unfunctional
	}
	
	public static FacadeService getInstance(){
		return oFacadeService;
		
	}
	
	public CustomerFacade getCustomerFacade(){
		return oCustomerFacade;
	}
}

import java.io.Serializable;

public class CustomerFacade implements Serializable {
	private static final long serialVersionUID = 1L;

	private final CustomerFacade oCustomerFacade = new CustomerFacade();
	
	public CustomerFacade(){
		this.ignition();
	}
	
	private void ignition() {
		// load data at startup from DB
	}

	public CustomerFacade getInstance(){
		return oCustomerFacade;
	}
}

- now your complete GUI should read from this facade:

private CustomerFacade getCustomerFacade(){
  return FacadeService.getInstance().getCustomerFacade();
}

- Make sure you can store everything at runtime. Create objects that dublicate each object in the database.
- make sure you are reading the DB at startup to fill your facade.
- make sure you are writing to the DB each time a value changes. You can set up for that general methods that help you. Even a class "DatabaseConnector" would be helpful to gather all the read/write/modify methods. make sure the DB actions are made asynchronous (Threading[^]) so they do not block your application.
- make sure your GUI is not reading from the DB aside of the facade. Your application should be able to run without the DB/just from the Facade data (the facade is empty if the database could not be read).

NOTE:
I know that this is not the intended use of Serializable and the design is not general applicable. But it's a simple, easy to implement approach to add a facade to an existing application.