Initial commit.

Author: yuelchen

design-patterns [complete]/pom.xml

@@ -0,0 +1,31 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+ <groupId>com.yuelchen</groupId>
+ <artifactId>design-patterns</artifactId>
+ <version>0.0.1-SNAPSHOT</version>
+ <name>practice-mathematics</name>
+ <description>A project for reviewing design patterns.</description>
+ 
+ <build>
+ <plugins>
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-compiler-plugin</artifactId>
+ <configuration>
+ <source>1.13</source>
+ <target>1.13</target>
+ </configuration>
+ </plugin>
+ </plugins>
+ </build>
+ 
+	<dependencies>
+	<dependency>
+	<groupId>junit</groupId>
+ <artifactId>junit</artifactId>
+ <version>4.13.1</version>
+	<scope>test</scope>
+	</dependency>
+	</dependencies>
+ 
+</project>

design-patterns [complete]/src/main/java/com/yuelchen/command/MarketMaker.java

@@ -0,0 +1,86 @@
+package com.yuelchen.command;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+public class MarketMaker {
+
+/**
+ * The Singleton object for MarketMaker. 
+ */
+public static MarketMaker marketMaker;
+
+//====================================================================================================
+
+/**
+ * A queue of order objects. 
+ */
+private Queue<Order> orders;
+
+//====================================================================================================
+
+/**
+ * Private class constructor.
+ */
+private MarketMaker() {
+this.orders = new LinkedList<>();
+}
+
+//====================================================================================================
+
+/**
+ * Singleton method, returns the MarketMaker object. 
+ * 
+ * @return	A MarketMaker object. 
+ */
+public static MarketMaker getInstance() {
+if(marketMaker == null) {
+marketMaker = new MarketMaker();
+}
+
+return marketMaker;
+}
+
+//====================================================================================================
+
+/**
+ * Adds the given order to the queue of orders. 
+ * 
+ * @param order	The order to be added. 
+ */
+public void place(Order order) {
+this.orders.add(order);
+}
+
+//====================================================================================================
+
+/**
+ * Removes the given order from the queue of orders if it exists and returns true, 
+ * otherwise returns false. 
+ * 
+ * @param order	The order to be removed. 
+ * 
+ * @return	True if the order was removed, otherwise returns false. 
+ */
+public boolean remove(Order order) {
+if(this.orders.contains(order)) {
+this.orders.remove(order);
+return true;
+}
+
+return false;
+}
+
+//====================================================================================================
+
+/**
+ * Executes all orders in queue and clears it. 
+ */
+public void execute() {
+for(Order order : this.orders) {
+order.execute();
+}
+
+this.orders.clear();
+}
+}

design-patterns [complete]/src/main/java/com/yuelchen/command/Order.java

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+package com.yuelchen.command;
+
+public interface Order {
+
+/**
+ * Executes the order. 
+ */
+public void execute();
+}

design-patterns [complete]/src/main/java/com/yuelchen/command/OrderBuy.java

@@ -0,0 +1,29 @@
+package com.yuelchen.command;
+
+public class OrderBuy implements Order {
+
+/**
+ * The trade object for this buy order. 
+ */
+private Trade trade;
+
+//====================================================================================================
+
+/**
+ * Class constructor. 
+ * 
+ * @param trade	The trade object. 
+ */
+public OrderBuy(Trade trade) {
+this.trade = trade;
+}
+
+//====================================================================================================
+
+/**
+ * Executes the buy option for trade order. 
+ */
+public void execute() {
+this.trade.buy();
+}
+}

design-patterns [complete]/src/main/java/com/yuelchen/command/OrderSell.java

@@ -0,0 +1,29 @@
+package com.yuelchen.command;
+
+public class OrderSell implements Order {
+
+/**
+ * The trade object for this sell order. 
+ */
+private Trade trade;
+
+//====================================================================================================
+
+/**
+ * Class constructor.
+ * 
+ * @param trade	The trade object. 
+ */
+public OrderSell(Trade trade) {
+this.trade = trade;
+}
+
+//====================================================================================================
+
+/**
+ * Executes the sell option for trade order. 
+ */
+public void execute() {
+this.trade.sell();
+}
+}

design-patterns [complete]/src/main/java/com/yuelchen/command/Trade.java

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+package com.yuelchen.command;
+
+public class Trade {
+
+/**
+ * The ticker symbol of the stock for this trade. 
+ */
+private String tickerSymbol;
+
+//====================================================================================================
+
+/**
+ * The number of shares for this trade. 
+ */
+private double shares;
+
+//====================================================================================================
+
+/**
+ * Class constructor. 
+ * 
+ * @param tickerSymbol	The stock ticker symbol.
+ * @param shares	The number of shares. 
+ */
+public Trade(String tickerSymbol, double shares) {
+this.tickerSymbol = tickerSymbol;
+this.shares = shares;
+}
+
+//====================================================================================================
+
+/**
+ * Returns the ticker symbol of the stock for this trade.
+ * 
+ * @return	The stock ticker symbol. 
+ */
+public String getTickerSymbol() {
+return this.tickerSymbol;
+}
+
+//====================================================================================================
+
+/**
+ * Returns the number of shares for this trade. 
+ * 
+ * @return	The number of shares. 
+ */
+public double getShares() {
+return this.shares;
+}
+
+//====================================================================================================
+
+/**
+ * Executes this trade as a purchase (buy). 
+ */
+public void buy() {
+System.out.println(String.format("Buying %d shares of %s", this.shares, this.tickerSymbol));
+}
+
+//====================================================================================================
+
+/**
+ * Executes this trade as a sale (sell). 
+ */
+public void sell() {
+System.out.println(String.format("Selling %d shares of %s", this.shares, this.tickerSymbol));
+}
+}

design-patterns [complete]/src/main/java/com/yuelchen/factory/Factory.java

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+package com.yuelchen.factory;
+
+public class Factory {
+
+/**
+ * Returns a Shape if the given array of values meets a shape criteria. 
+ * 
+ * Array Length to Shape Name Relations:
+ * - 1 equals Square
+ * - 2 equals Rectangle
+ * - 3 equals Triangle
+ * 
+ * Otherwise returns null. 
+ * 
+ * @param values	The array of values to be assigned to a known Shape.
+ * 
+ * @return	A Shape object if criteria is met, or otherwise returns null. 
+ */
+public static Shape getShape(double[] values) {
+if(values.length == 1) {
+return new ShapeSquare(values[0]);
+} else if(values.length == 2) {
+return new ShapeRectangle(values[0], values[1]);
+} else if(values.length == 3) {
+return new ShapeTriangle(values[0], values[1], values[3]);
+}
+
+return null;
+}
+}

design-patterns [complete]/src/main/java/com/yuelchen/factory/Shape.java

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+package com.yuelchen.factory;
+
+public interface Shape {
+
+/**
+ * Determines and returns the perimeter of the Shape. 
+ * 
+ * @return	The perimeter of the Shape. 
+ */
+public double getPerimeter();
+}

design-patterns [complete]/src/main/java/com/yuelchen/factory/ShapeRectangle.java

@@ -0,0 +1,73 @@
+package com.yuelchen.factory;
+
+public class ShapeRectangle implements Shape {
+
+/**
+ * The length of a rectangle. 
+ */
+private double length;
+
+//====================================================================================================
+
+/**
+ * The width of a rectangle. 
+ */
+private double width;
+
+//====================================================================================================
+
+/**
+ * Class constructor. 
+ * 
+ * @param length	The length of the rectangle. 
+ * @param width	The width of the rectangle.
+ */
+public ShapeRectangle(double length, double width) {
+this.length = length;
+this.width = width;
+}
+
+//====================================================================================================
+
+/**
+ * Returns the length of the rectangle. 
+ * 
+ * @return	The length of the rectangle.
+ */
+public double getLength() {
+return this.length;
+}
+
+//====================================================================================================
+
+/**
+ * Returns the width of the rectangle. 
+ * 
+ * @return	The width of the rectangle. 
+ */
+public double getWidth() {
+return this.width;
+}
+
+//====================================================================================================
+
+/**
+ * Determines and returns the perimeter of the rectangle. 
+ * 
+ * @return	The perimeter of the rectangle. 
+ */
+public double getPerimeter() {
+return 2 * (this.length + this.width);
+}
+
+//====================================================================================================
+
+/**
+ * Determines and returns the area if the rectangle.
+ * 
+ * @return	The area of the rectangle. 
+ */
+public double getArea() {
+return this.length * this.width;
+}
+}