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diff --git a/java/com/android/contacts/common/Collapser.java b/java/com/android/contacts/common/Collapser.java
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+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.contacts.common;
+
+import android.content.Context;
+import java.util.Iterator;
+import java.util.List;
+
+/**
+ * Class used for collapsing data items into groups of similar items. The data items that should be
+ * collapsible should implement the Collapsible interface. The class also contains a utility
+ * function that takes an ArrayList of items and returns a list of the same items collapsed into
+ * groups.
+ */
+public final class Collapser {
+
+  /*
+   * The Collapser uses an n^2 algorithm so we don't want it to run on
+   * lists beyond a certain size. This specifies the maximum size to collapse.
+   */
+  private static final int MAX_LISTSIZE_TO_COLLAPSE = 20;
+
+  /*
+   * This utility class cannot be instantiated.
+   */
+  private Collapser() {}
+
+  /**
+   * Collapses a list of Collapsible items into a list of collapsed items. Items are collapsed if
+   * {@link Collapsible#shouldCollapseWith(Object)} returns true, and are collapsed through the
+   * {@Link Collapsible#collapseWith(Object)} function implemented by the data item.
+   *
+   * @param list List of Objects of type <T extends Collapsible<T>> to be collapsed.
+   */
+  public static <T extends Collapsible<T>> void collapseList(List<T> list, Context context) {
+
+    int listSize = list.size();
+    // The algorithm below is n^2 so don't run on long lists
+    if (listSize > MAX_LISTSIZE_TO_COLLAPSE) {
+      return;
+    }
+
+    for (int i = 0; i < listSize; i++) {
+      T iItem = list.get(i);
+      if (iItem != null) {
+        for (int j = i + 1; j < listSize; j++) {
+          T jItem = list.get(j);
+          if (jItem != null) {
+            if (iItem.shouldCollapseWith(jItem, context)) {
+              iItem.collapseWith(jItem);
+              list.set(j, null);
+            } else if (jItem.shouldCollapseWith(iItem, context)) {
+              jItem.collapseWith(iItem);
+              list.set(i, null);
+              break;
+            }
+          }
+        }
+      }
+    }
+
+    // Remove the null items
+    Iterator<T> itr = list.iterator();
+    while (itr.hasNext()) {
+      if (itr.next() == null) {
+        itr.remove();
+      }
+    }
+  }
+
+  /*
+   * Interface implemented by data types that can be collapsed into groups of similar data. This
+   * can be used for example to collapse similar contact data items into a single item.
+   */
+  public interface Collapsible<T> {
+
+    void collapseWith(T t);
+
+    boolean shouldCollapseWith(T t, Context context);
+  }
+}