Fixes to pull request #2

.gitignore

@@ -4,3 +4,9 @@
 *.jar
 *.war
 *.ear
+
+# Ignore . & ~ files except .gitignore #
+*~
+.*
+target/
+!/.gitignore

pom.xml

@@ -28,16 +28,17 @@
 	</build>
 
 	<dependencies>
+		<dependency>
+			<groupId>junit</groupId>
+			<artifactId>junit</artifactId>
+			<version>4.11</version>
+			<scope>test</scope>
+		</dependency>
+
 		<dependency>
 			<groupId>org.glassfish</groupId>
 			<artifactId>javax.json</artifactId>
 			<version>1.0-b02</version>
 		</dependency>
-
-		<!-- <dependency> 
-		     <groupId>javax</groupId> 
-		     <artifactId>javaee-api</artifactId> 
-			 <version>7.0-b72</version> 
-	    </dependency> -->
 	</dependencies>
 </project>

src/main/java/JSR353/JSON/PricesCacheStore.java

@@ -2,38 +2,36 @@
 
 import java.util.concurrent.ConcurrentHashMap;
 
-public class PricesCacheStore {
-
-	private final static PricesCacheStore INSTANCE = new PricesCacheStore();	
-
-	private PricesCacheStore() {}
-	private volatile String lastSymboleUpdated;
-
-	// will contain Symbols and prices stored and constantly updated	
-	private volatile ConcurrentHashMap<String, Double> pricesCache = new ConcurrentHashMap<>(); 
-
-	public static PricesCacheStore getInstance() {
-		return INSTANCE; 
-	}
-
+public enum PricesCacheStore {
+
+	INSTANCE;
+
+	private volatile String lastSymbolUpdated;
+
+	// will contain Symbols and prices stored and constantly updated
+	private ConcurrentHashMap<String, Double> pricesCache = new ConcurrentHashMap<>();
+
 	public void addPrice(String symbol, Double price) {
-		pricesCache.put(symbol, price);
-		lastSymboleUpdated = symbol; 
+		if (symbol != null && price != null) {
+		    pricesCache.put(symbol, price);
+		    lastSymbolUpdated = symbol;
+		}
 	}
-	
+
 	public Double getPrice(String symbol) {
+		if (symbol == null) {
+			return 0d;
+		}
 		Double price = pricesCache.get(symbol);
-		return price == null ? 0 : price;
+		return price == null ? 0d : price;
 	}
-
-	// Keep in mind immutability - return a copy of the object
-	// does not matter if it is static or volatile
-	// or if its threading is safe
-	public ConcurrentHashMap<String, Double> getAllPrices() {		
-		return new ConcurrentHashMap<String, Double>(pricesCache);
+
+	// Object is threading is safe so can be returned as it is
+	public ConcurrentHashMap<String, Double> getAllPrices() {
+		return pricesCache;
 	}
-	
+
 	public String getLastSymbolUpdated() {
-		return new String(lastSymboleUpdated);
+		return new String(lastSymbolUpdated);
 	}
 }