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-rw-r--r--src/com/android/launcher3/model/AbstractUserComparator.java67
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diff --git a/src/com/android/launcher3/model/AbstractUserComparator.java b/src/com/android/launcher3/model/AbstractUserComparator.java
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+/*
+ * Copyright (C) 2015 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.launcher3.model;
+
+import android.content.Context;
+
+import com.android.launcher3.ItemInfo;
+import com.android.launcher3.compat.UserHandleCompat;
+import com.android.launcher3.compat.UserManagerCompat;
+
+import java.util.Comparator;
+import java.util.HashMap;
+
+/**
+ * A comparator to arrange items based on user profiles.
+ */
+public abstract class AbstractUserComparator<T extends ItemInfo> implements Comparator<T> {
+
+ private HashMap<UserHandleCompat, Long> mUserSerialCache = new HashMap<>();
+ private final UserManagerCompat mUserManager;
+ private final UserHandleCompat mMyUser;
+
+ public AbstractUserComparator(Context context) {
+ mUserManager = UserManagerCompat.getInstance(context);
+ mMyUser = UserHandleCompat.myUserHandle();
+ }
+
+ @Override
+ public int compare(T lhs, T rhs) {
+ if (mMyUser.equals(lhs.user)) {
+ return -1;
+ } else {
+ Long aUserSerial = getAndCacheUserSerial(lhs.user);
+ Long bUserSerial = getAndCacheUserSerial(rhs.user);
+ return aUserSerial.compareTo(bUserSerial);
+ }
+ }
+
+ /**
+ * Returns the user serial for this user, using a cached serial if possible.
+ */
+ private Long getAndCacheUserSerial(UserHandleCompat user) {
+ Long userSerial = mUserSerialCache.get(user);
+ if (userSerial == null) {
+ userSerial = mUserManager.getSerialNumberForUser(user);
+ mUserSerialCache.put(user, userSerial);
+ }
+ return userSerial;
+ }
+
+ public void clearUserCache() {
+ mUserSerialCache.clear();
+ }
+}