1/* 2 * Copyright (C) 2015 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 17package android.support.v7.preference; 18 19import android.content.Context; 20import android.support.v4.content.res.TypedArrayUtils; 21import android.util.AttributeSet; 22 23/** 24 * Represents a top-level {@link Preference} that 25 * is the root of a Preference hierarchy. A {@link PreferenceFragmentCompat} 26 * points to an instance of this class to show the preferences. To instantiate 27 * this class, use {@link PreferenceManager#createPreferenceScreen(android.content.Context)}. 28 * <ul> 29 * This class can appear in two places: 30 * <li> When a {@link PreferenceFragmentCompat} points to this, it is used as the root 31 * and is not shown (only the contained preferences are shown). 32 * <li> When it appears inside another preference hierarchy, it is shown and 33 * serves as the gateway to another screen of preferences (either by showing 34 * another screen of preferences as a {@link android.app.Dialog} or via a 35 * {@link android.content.Context#startActivity(android.content.Intent)} from the 36 * {@link Preference#getIntent()}). The children of this {@link PreferenceScreen} 37 * are NOT shown in the screen that this {@link PreferenceScreen} is shown in. 38 * Instead, a separate screen will be shown when this preference is clicked. 39 * </ul> 40 * <p>Here's an example XML layout of a PreferenceScreen:</p> 41 * <pre> 42 <PreferenceScreen 43 xmlns:android="http://schemas.android.com/apk/res/android" 44 android:key="first_preferencescreen"> 45 <CheckBoxPreference 46 android:key="wifi enabled" 47 android:title="WiFi" /> 48 <PreferenceScreen 49 android:key="second_preferencescreen" 50 android:title="WiFi settings"> 51 <CheckBoxPreference 52 android:key="prefer wifi" 53 android:title="Prefer WiFi" /> 54 ... other preferences here ... 55 </PreferenceScreen> 56 </PreferenceScreen> </pre> 57 * <p> 58 * In this example, the "first_preferencescreen" will be used as the root of the 59 * hierarchy and given to a {@link android.support.v14.preference.PreferenceFragment} 60 * or {@link PreferenceFragmentCompat}. 61 * The first screen will 62 * show preferences "WiFi" (which can be used to quickly enable/disable WiFi) 63 * and "WiFi settings". The "WiFi settings" is the "second_preferencescreen" and when 64 * clicked will show another screen of preferences such as "Prefer WiFi" (and 65 * the other preferences that are children of the "second_preferencescreen" tag). 66 * 67 * <div class="special reference"> 68 * <h3>Developer Guides</h3> 69 * <p>For information about building a settings UI with Preferences, 70 * read the <a href="{@docRoot}guide/topics/ui/settings.html">Settings</a> 71 * guide.</p> 72 * </div> 73 * 74 * @see PreferenceCategory 75 */ 76public final class PreferenceScreen extends PreferenceGroup { 77 78 private boolean mShouldUseGeneratedIds = true; 79 80 /** 81 * Do NOT use this constructor, use {@link PreferenceManager#createPreferenceScreen(Context)}. 82 * @hide- 83 */ 84 public PreferenceScreen(Context context, AttributeSet attrs) { 85 super(context, attrs, TypedArrayUtils.getAttr(context, R.attr.preferenceScreenStyle, 86 android.R.attr.preferenceScreenStyle)); 87 } 88 89 @Override 90 protected void onClick() { 91 if (getIntent() != null || getFragment() != null || getPreferenceCount() == 0) { 92 return; 93 } 94 final PreferenceManager.OnNavigateToScreenListener listener = 95 getPreferenceManager().getOnNavigateToScreenListener(); 96 if (listener != null) { 97 listener.onNavigateToScreen(this); 98 } 99 } 100 101 @Override 102 protected boolean isOnSameScreenAsChildren() { 103 return false; 104 } 105 106 /** 107 * See {@link #setShouldUseGeneratedIds(boolean)} 108 * @return {@code true} if the adapter should use the preference IDs generated by 109 * {@link PreferenceGroup#addPreference(Preference)} as stable item IDs 110 */ 111 public boolean shouldUseGeneratedIds() { 112 return mShouldUseGeneratedIds; 113 } 114 115 /** 116 * Set whether the adapter created for this screen should attempt to use the preference IDs 117 * generated by {@link PreferenceGroup#addPreference(Preference)} as stable item IDs. Setting 118 * this to false can suppress unwanted animations if {@link Preference} objects are frequently 119 * removed from and re-added to their containing {@link PreferenceGroup}. 120 * <p> 121 * This method may only be called when the preference screen is not attached to the hierarchy. 122 * <p> 123 * Default value is {@code true}. 124 * 125 * @param shouldUseGeneratedIds {@code true} if the adapter should use the preference ID as a 126 * stable ID, or {@code false} to disable the use of 127 * stable IDs 128 */ 129 public void setShouldUseGeneratedIds(boolean shouldUseGeneratedIds) { 130 if (isAttached()) { 131 throw new IllegalStateException("Cannot change the usage of generated IDs while" + 132 " attached to the preference hierarchy"); 133 } 134 mShouldUseGeneratedIds = shouldUseGeneratedIds; 135 } 136} 137