1 files changed, 67 insertions, 0 deletions
diff --git a/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/collection/MoveableArrayList.java b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/collection/MoveableArrayList.java
new file mode 100644
index 0000000000..62d42d3bb0
--- /dev/null
+++ b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/util/collection/MoveableArrayList.java
@@ -0,0 +1,67 @@
+package org.eclipse.net4j.util.collection;
+
+import java.util.ArrayList;
+
+/**
+ * A list with O(1) effort for random access.
+ * 
+ * @author Eike Stepper
+ */
+public final class MoveableArrayList<E> extends ArrayList<E> implements MoveableList<E>
+{
+  private static final long serialVersionUID = 1L;
+
+  public MoveableArrayList(int initialCapacity)
+  {
+    super(initialCapacity);
+
+  }
+
+  public E move(int targetIndex, int sourceIndex)
+  {
+    int size = size();
+    if (sourceIndex >= size)
+    {
+      throw new IndexOutOfBoundsException("sourceIndex=" + sourceIndex + ", size=" + size);
+    }
+
+    if (targetIndex >= size)
+    {
+      throw new IndexOutOfBoundsException("targetIndex=" + targetIndex + ", size=" + size);
+    }
+
+    E object = get(sourceIndex);
+    if (targetIndex == sourceIndex)
+    {
+      return object;
+    }
+
+    if (targetIndex < sourceIndex)
+    {
+      moveUp1(targetIndex, sourceIndex - targetIndex);
+    }
+    else
+    {
+      moveDown1(targetIndex, targetIndex - sourceIndex);
+    }
+
+    set(targetIndex, object);
+    return object;
+  }
+
+  private void moveUp1(int index, int count)
+  {
+    for (int i = count; i > 0; i--)
+    {
+      set(index + i, get(index + i - 1));
+    }
+  }
+
+  private void moveDown1(int index, int count)
+  {
+    for (int i = count; i > 0; i--)
+    {
+      set(index - i, get(index - i + 1));
+    }
+  }
+}