Add getOrDefault() method

src/main/java/com/fewlaps/quitnowcache/QNCache.java

@@ -97,6 +97,18 @@ public T get(String key) {
         }
     }
 
+    /**
+     * Gets an element from the cache. If it's null, the default value will be returned instead.
+     */
+    public T getOrDefault(String key, T defaultValue) {
+        T value = get(key);
+        if (value == null) {
+            return defaultValue;
+        } else {
+            return value;
+        }
+    }
+
     /**
      * Gets an element from the cache. If the element exists but it's dead,
      * it will be removed from the cache to free memory. It could call

src/test/java/com/fewlaps/quitnowcache/GetOrDefaultTest.java

@@ -0,0 +1,34 @@
+package com.fewlaps.quitnowcache;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class GetOrDefaultTest extends BaseTest {
+
+    QNCache<String> cache;
+
+    @Before
+    public void init() {
+        cache = new QNCacheBuilder().createQNCache();
+    }
+
+    @Test
+    public void valueIsReturnedIfItsPresent() {
+        cache.set(A_KEY, A_VALUE, ONE_SECOND);
+
+        String result = cache.getOrDefault(A_KEY, "nothing");
+
+        assertEquals(A_VALUE, result);
+    }
+
+    @Test
+    public void defaultIsReturnedIfValueIsNotPresent() {
+        cache.remove(A_KEY);
+
+        String result = cache.getOrDefault(A_KEY, "nothing");
+
+        assertEquals("nothing", result);
+    }
+}