1 files changed, 137 insertions, 0 deletions
diff --git a/src/de/fhswf/in/inf/java1/aufgabe06/ListBenchmark.java b/src/de/fhswf/in/inf/java1/aufgabe06/ListBenchmark.java
new file mode 100644
index 0000000..b03b68d
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+++ b/src/de/fhswf/in/inf/java1/aufgabe06/ListBenchmark.java
@@ -0,0 +1,137 @@
+/**
+ * 
+ */
+package de.fhswf.in.inf.java1.aufgabe06;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Random;
+import java.util.Vector;
+
+/**
+ * Class that benchmarks List implementations.
+ *
+ * @author $Author: $
+ * @version $Revision: $, $Date: $ UTC
+ */
+public final class ListBenchmark
+{
+
+   private static final Integer TESTOBJ = new Integer(214);
+
+   /**
+    * Prevents instantiation of the utility class.
+    *
+    */
+   private ListBenchmark()
+   {
+   }
+
+   /**
+    * Starts a benchmark of different Lists and different test cases.
+    *
+    */
+   public static void startBenchmark()
+   {
+      final int times = 100000;
+
+      benchmarkGrouping("ArrayList", new ArrayList<Integer>(times), times);
+      benchmarkGrouping("Vector", new Vector<Integer>(times), times);
+      benchmarkGrouping("LinkedList", new LinkedList<Integer>(), times);
+
+   }
+
+   /**
+    * Groups the 3 different benchmark versions together.
+    *
+    * @param variant
+    *           Name of the list type.
+    * @param list
+    *           The list which will be benchmarked.
+    * @param times
+    *           How often will be inserted.
+    */
+   private static void benchmarkGrouping(String variant, List<Integer> list,
+         int times)
+   {
+      System.out.print(variant + " am Anfang: ");
+      System.out.println(benchmarkAtBeginning(list, times) + " ms");
+      System.out.print(variant + " am Ende: ");
+      System.out.println(benchmarkAtEnding(list, times) + " ms");
+      System.out.print(variant + " zufälliger Index: ");
+      System.out.println(benchmarkAtRandom(list, times) + " ms");
+   }
+
+   /**
+    * Inserts new value at the beginning of the list.
+    *
+    * @param list
+    *           List to be tested.
+    * @param times
+    *           How many inserts are done.
+    * @return Time in milliseconds that the action took.
+    */
+   private static long benchmarkAtBeginning(List<Integer> list, int times)
+   {
+      long start = System.currentTimeMillis(); // Gets current time in µs
+
+      for (int i = 0; i < times; i++)
+      {
+         list.add(0, TESTOBJ);
+      }
+
+      return (System.currentTimeMillis() - start); // Returns runtime
+   }
+
+   /**
+    * Inserts new value at the end of the list.
+    *
+    * @param list
+    *           List to be tested.
+    * @param times
+    *           How many inserts are done.
+    * @return Time in milliseconds that the action took.
+    */
+   private static long benchmarkAtEnding(List<Integer> list, int times)
+   {
+      long start = System.currentTimeMillis(); // Gets current time in µs
+
+      for (int i = 0; i < times; i++)
+      {
+         list.add(TESTOBJ);
+      }
+
+      return (System.currentTimeMillis() - start); // Returns runtime
+   }
+
+   /**
+    * Inserts new value at a random index of the list.
+    *
+    * @param list
+    *           List to be tested.
+    * @param times
+    *           How many inserts are done.
+    * @return Time in milliseconds that the action took.
+    */
+   private static long benchmarkAtRandom(List<Integer> list, int times)
+   {
+
+      int[] randVal = new int[times];
+      Random rand = new Random();
+
+      for (int i = 0; i < randVal.length; i++)
+      {
+         randVal[i] = rand.nextInt(list.size() + i + 1);
+      }
+
+      long start = System.currentTimeMillis(); // Gets current time in µs
+
+      for (int i = 0; i < times; i++)
+      {
+         list.add(randVal[i], TESTOBJ);
+      }
+
+      return (System.currentTimeMillis() - start); // Returns runtime
+   }
+}