/* * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt). * * The MIT License * Copyright © 2014-2022 Ilkka Seppälä * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package com.iluwatar.roleobject; import static com.iluwatar.roleobject.Role.BORROWER; import static com.iluwatar.roleobject.Role.INVESTOR; import lombok.extern.slf4j.Slf4j; /** * The Role Object pattern suggests to model context-specific views of an object as separate role * objects which are dynamically attached to and removed from the core object. We call the resulting * composite object structure, consisting of the core and its role objects, a subject. A subject * often plays several roles and the same role is likely to be played by different subjects. As an * example consider two different customers playing the role of borrower and investor, respectively. * Both roles could as well be played by a single {@link Customer} object. The common superclass for * customer-specific roles is provided by {@link CustomerRole}, which also supports the {@link * Customer} interface. * *
The {@link CustomerRole} class is abstract and not meant to be instantiated. Concrete * subclasses of {@link CustomerRole}, for example {@link BorrowerRole} or {@link InvestorRole}, * define and implement the interface for specific roles. It is only these subclasses which are * instantiated at runtime. The {@link BorrowerRole} class defines the context-specific view of * {@link Customer} objects as needed by the loan department. It defines additional operations to * manage the customer’s credits and securities. Similarly, the {@link InvestorRole} class adds * operations specific to the investment department’s view of customers. A client like the loan * application may either work with objects of the {@link CustomerRole} class, using the interface * class {@link Customer}, or with objects of concrete {@link CustomerRole} subclasses. Suppose the * loan application knows a particular {@link Customer} instance through its {@link Customer} * interface. The loan application may want to check whether the {@link Customer} object plays the * role of Borrower. To this end it calls {@link Customer#hasRole(Role)} with a suitable role * specification. For the purpose of our example, let’s assume we can name roles with enum. If the * {@link Customer} object can play the role named “Borrower,” the loan application will ask it to * return a reference to the corresponding object. The loan application may now use this reference * to call Borrower-specific operations. */ @Slf4j public class ApplicationRoleObject { /** * Main entry point. * * @param args program arguments */ public static void main(String[] args) { var customer = Customer.newCustomer(BORROWER, INVESTOR); LOGGER.info("New customer created : {}", customer); var hasBorrowerRole = customer.hasRole(BORROWER); LOGGER.info("Customer has a borrower role - {}", hasBorrowerRole); var hasInvestorRole = customer.hasRole(INVESTOR); LOGGER.info("Customer has an investor role - {}", hasInvestorRole); customer .getRole(INVESTOR, InvestorRole.class) .ifPresent( inv -> { inv.setAmountToInvest(1000); inv.setName("Billy"); }); customer.getRole(BORROWER, BorrowerRole.class).ifPresent(inv -> inv.setName("Johny")); customer .getRole(INVESTOR, InvestorRole.class) .map(InvestorRole::invest) .ifPresent(LOGGER::info); customer .getRole(BORROWER, BorrowerRole.class) .map(BorrowerRole::borrow) .ifPresent(LOGGER::info); } }