#1313 Add Separated Interface design pattern

separated-interface/src/main/java/com/iluwatar/separatedinterface/App.java

@@ -0,0 +1,61 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2019 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.separatedinterface;
+
+import com.iluwatar.separatedinterface.invoice.InvoiceGenerator;
+import com.iluwatar.separatedinterface.taxes.DomesticTax;
+import com.iluwatar.separatedinterface.taxes.ForeignTax;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>The Strategy pattern (also known as the policy pattern) is a software design pattern that
+ * enables an algorithm's behavior to be selected at runtime.</p>
+ *
+ * <p>Before Java 8 the Strategies needed to be separate classes forcing the developer
+ * to write lots of boilerplate code. With modern Java it is easy to pass behavior with method
+ * references and lambdas making the code shorter and more readable.</p>
+ *
+ */
+public class App {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
+  public static final double PRODUCT_COST = 50.0;
+
+  /**
+   * Program entry point.
+   *
+   * @param args command line args
+   */
+  public static void main(String[] args) {
+    //Create the invoice generator with product cost as 50 and foreign product tax
+    var internationalProductInvoice = new InvoiceGenerator(PRODUCT_COST, new ForeignTax());
+    LOGGER.info("Foreign Tax applied: {}", "" + internationalProductInvoice.getAmountWithTax());
+
+    //Create the invoice generator with product cost as 50 and domestic product tax
+    var domesticProductInvoice = new InvoiceGenerator(PRODUCT_COST, new DomesticTax());
+    LOGGER.info("Domestic Tax applied: {}", "" + domesticProductInvoice.getAmountWithTax());
+  }
+}