#108 Consistent package naming throughout the examples

object-pool/src/main/java/com/iluwatar/object/pool/ObjectPool.java

@@ -0,0 +1,37 @@
+package com.iluwatar.object.pool;
+
+import java.util.HashSet;
+
+/**
+ * 
+ * Generic object pool
+ *
+ * @param <T>
+ */
+public abstract class ObjectPool<T> {
+
+	private HashSet<T> available = new HashSet<>();
+	private HashSet<T> inUse = new HashSet<>();
+	
+	protected abstract T create();
+	
+	public synchronized T checkOut() {
+		if (available.size() <= 0) {
+			available.add(create());
+		}
+		T instance = available.iterator().next();
+		available.remove(instance);
+		inUse.add(instance);
+		return instance;
+	}
+	
+	public synchronized void checkIn(T instance) {
+		inUse.remove(instance);
+		available.add(instance);
+	}
+	
+	@Override
+	public String toString() {
+		return String.format("Pool available=%d inUse=%d", available.size(), inUse.size());
+	}
+}