1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.storagemanager.utils; 18 19 import android.support.v7.preference.Preference; 20 import android.support.v7.preference.PreferenceGroup; 21 import android.text.TextUtils; 22 import android.util.ArrayMap; 23 24 /** 25 * The PreferenceListCache is a cache of preferences sourced from a {@link PreferenceGroup} which 26 * allows for the re-use of the same preference object when re-creating a list of preferences. 27 */ 28 public class PreferenceListCache { 29 private PreferenceGroup mGroup; 30 private ArrayMap<String, Preference> mCache; 31 32 /** 33 * Constructs a PreferenceListCache using the preferences within the given PreferenceGroup. 34 * @param group The preference group to source preferences from. 35 */ 36 public PreferenceListCache(PreferenceGroup group) { 37 mGroup = group; 38 mCache = new ArrayMap<>(); 39 final int N = group.getPreferenceCount(); 40 for (int i = 0; i < N; i++) { 41 Preference p = group.getPreference(i); 42 String key = p.getKey(); 43 if (TextUtils.isEmpty(key) || mCache.containsKey(key)) { 44 throw new IllegalArgumentException( 45 "Invalid key encountered in preference group " + group.getKey()); 46 } 47 mCache.put(p.getKey(), p); 48 } 49 } 50 51 /** 52 * Removes a cached preferenced from the cache, if it exists. 53 * @param key The key of the preference. 54 * @return The preference, if it exists in the cache, or null. 55 */ 56 public Preference getCachedPreference(String key) { 57 return mCache.remove(key); 58 } 59 60 /** 61 * Removes the un-reused preferences from the original PreferenceGroup. 62 */ 63 public void removeCachedPrefs() { 64 for (Preference p : mCache.values()) { 65 mGroup.removePreference(p); 66 } 67 } 68 } 69
