Containers in Depth: Exercise 37

ContainersInDepth/HashMapTest.java

@@ -0,0 +1,41 @@
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+public class HashMapTest {
+
+    private void test(int initialCapacity, float loadFactor, int size) {
+        HashMap<String, String> hashMap = new HashMap(initialCapacity, loadFactor);
+        fillHashMap(hashMap, size);
+        long duration = countSearchingTime(hashMap);
+        String result = String.format("Searching in HashMap [size = %d, capacity = %d, loadFactor = %f] in %d nanoseconds on average",
+                size, initialCapacity, loadFactor, duration);
+        Util.println(result);
+    }
+
+    private void fillHashMap(HashMap<String, String> hashMap, int size) {
+        hashMap.putAll(Countries.capitals(size));
+    }
+
+    private long countSearchingTime(HashMap<String, String> hashMap) {
+        Set<Map.Entry<String, String>> entrySet = hashMap.entrySet();
+        long startTime = getCurrentTime();
+        for (Map.Entry entry : entrySet) {
+            hashMap.get(entry.getKey());
+        }
+        long duration = getCurrentTime() - startTime;
+        return duration / entrySet.size();
+    }
+
+    private long getCurrentTime() {
+        return System.nanoTime();
+    }
+
+    public static void main(String[] args) {
+        HashMapTest hashMapTest = new HashMapTest();
+        int capitalsSize = Countries.capitals().size();
+        hashMapTest.test(capitalsSize, 1.75f, capitalsSize);
+        hashMapTest.test(2 * capitalsSize, 1.75f, capitalsSize);
+        hashMapTest.test(capitalsSize, 0.25f, capitalsSize);
+    }
+}