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Activity.java
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Activity.java
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/*
* Copyright (C) 2006 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 android.app;
import static android.Manifest.permission.CONTROL_REMOTE_APP_TRANSITION_ANIMATIONS;
import static java.lang.Character.MIN_VALUE;
import android.annotation.CallSuper;
import android.annotation.DrawableRes;
import android.annotation.IdRes;
import android.annotation.IntDef;
import android.annotation.LayoutRes;
import android.annotation.MainThread;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.RequiresPermission;
import android.annotation.StyleRes;
import android.annotation.SystemApi;
import android.app.VoiceInteractor.Request;
import android.app.admin.DevicePolicyManager;
import android.app.assist.AssistContent;
import android.content.ComponentCallbacks2;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.CursorLoader;
import android.content.IIntentSender;
import android.content.Intent;
import android.content.IntentSender;
import android.content.SharedPreferences;
import android.content.pm.ActivityInfo;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.media.AudioManager;
import android.media.session.MediaController;
import android.net.Uri;
import android.os.BadParcelableException;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Parcelable;
import android.os.PersistableBundle;
import android.os.RemoteException;
import android.os.ServiceManager.ServiceNotFoundException;
import android.os.StrictMode;
import android.os.SystemProperties;
import android.os.UserHandle;
import android.text.Selection;
import android.text.SpannableStringBuilder;
import android.text.TextUtils;
import android.text.method.TextKeyListener;
import android.transition.Scene;
import android.transition.TransitionManager;
import android.util.ArrayMap;
import android.util.AttributeSet;
import android.util.EventLog;
import android.util.Log;
import android.util.PrintWriterPrinter;
import android.util.Slog;
import android.util.SparseArray;
import android.util.SuperNotCalledException;
import android.view.ActionMode;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.ContextThemeWrapper;
import android.view.DragAndDropPermissions;
import android.view.DragEvent;
import android.view.KeyEvent;
import android.view.KeyboardShortcutGroup;
import android.view.KeyboardShortcutInfo;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.RemoteAnimationDefinition;
import android.view.SearchEvent;
import android.view.View;
import android.view.View.OnCreateContextMenuListener;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewManager;
import android.view.ViewRootImpl;
import android.view.ViewRootImpl.ActivityConfigCallback;
import android.view.Window;
import android.view.Window.WindowControllerCallback;
import android.view.WindowManager;
import android.view.WindowManagerGlobal;
import android.view.accessibility.AccessibilityEvent;
import android.view.autofill.AutofillId;
import android.view.autofill.AutofillManager;
import android.view.autofill.AutofillManager.AutofillClient;
import android.view.autofill.AutofillPopupWindow;
import android.view.autofill.IAutofillWindowPresenter;
import android.widget.AdapterView;
import android.widget.Toast;
import android.widget.Toolbar;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.app.IVoiceInteractor;
import com.android.internal.app.ToolbarActionBar;
import com.android.internal.app.WindowDecorActionBar;
import com.android.internal.policy.PhoneWindow;
import dalvik.system.VMRuntime;
import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
/**
* An activity is a single, focused thing that the user can do. Almost all
* activities interact with the user, so the Activity class takes care of
* creating a window for you in which you can place your UI with
* {@link #setContentView}. While activities are often presented to the user
* as full-screen windows, they can also be used in other ways: as floating
* windows (via a theme with {@link android.R.attr#windowIsFloating} set)
* or embedded inside of another activity (using {@link ActivityGroup}).
*
* There are two methods almost all subclasses of Activity will implement:
*
* <ul>
* <li> {@link #onCreate} is where you initialize your activity. Most
* importantly, here you will usually call {@link #setContentView(int)}
* with a layout resource defining your UI, and using {@link #findViewById}
* to retrieve the widgets in that UI that you need to interact with
* programmatically.
*
* <li> {@link #onPause} is where you deal with the user leaving your
* activity. Most importantly, any changes made by the user should at this
* point be committed (usually to the
* {@link android.content.ContentProvider} holding the data).
* </ul>
*
* <p>To be of use with {@link android.content.Context#startActivity Context.startActivity()}, all
* activity classes must have a corresponding
* {@link android.R.styleable#AndroidManifestActivity <activity>}
* declaration in their package's <code>AndroidManifest.xml</code>.</p>
*
* <p>Topics covered here:
* <ol>
* <li><a href="#Fragments">Fragments</a>
* <li><a href="#ActivityLifecycle">Activity Lifecycle</a>
* <li><a href="#ConfigurationChanges">Configuration Changes</a>
* <li><a href="#StartingActivities">Starting Activities and Getting Results</a>
* <li><a href="#SavingPersistentState">Saving Persistent State</a>
* <li><a href="#Permissions">Permissions</a>
* <li><a href="#ProcessLifecycle">Process Lifecycle</a>
* </ol>
*
* <div class="special reference">
* <h3>Developer Guides</h3>
* <p>The Activity class is an important part of an application's overall lifecycle,
* and the way activities are launched and put together is a fundamental
* part of the platform's application model. For a detailed perspective on the structure of an
* Android application and how activities behave, please read the
* <a href="{@docRoot}guide/topics/fundamentals.html">Application Fundamentals</a> and
* <a href="{@docRoot}guide/components/tasks-and-back-stack.html">Tasks and Back Stack</a>
* developer guides.</p>
*
* <p>You can also find a detailed discussion about how to create activities in the
* <a href="{@docRoot}guide/components/activities.html">Activities</a>
* developer guide.</p>
* </div>
*
* <a name="Fragments"></a>
* <h3>Fragments</h3>
*
* <p>The {@link android.support.v4.app.FragmentActivity} subclass
* can make use of the {@link android.support.v4.app.Fragment} class to better
* modularize their code, build more sophisticated user interfaces for larger
* screens, and help scale their application between small and large screens.</p>
*
* <p>For more information about using fragments, read the
* <a href="{@docRoot}guide/components/fragments.html">Fragments</a> developer guide.</p>
*
* <a name="ActivityLifecycle"></a>
* <h3>Activity Lifecycle</h3>
*
* <p>Activities in the system are managed as an <em>activity stack</em>.
* When a new activity is started, it is placed on the top of the stack
* and becomes the running activity -- the previous activity always remains
* below it in the stack, and will not come to the foreground again until
* the new activity exits.</p>
*
* <p>An activity has essentially four states:</p>
* <ul>
* <li> If an activity is in the foreground of the screen (at the top of
* the stack),
* it is <em>active</em> or <em>running</em>. </li>
* <li>If an activity has lost focus but is still visible (that is, a new non-full-sized
* or transparent activity has focus on top of your activity), it
* is <em>paused</em>. A paused activity is completely alive (it
* maintains all state and member information and remains attached to
* the window manager), but can be killed by the system in extreme
* low memory situations.
* <li>If an activity is completely obscured by another activity,
* it is <em>stopped</em>. It still retains all state and member information,
* however, it is no longer visible to the user so its window is hidden
* and it will often be killed by the system when memory is needed
* elsewhere.</li>
* <li>If an activity is paused or stopped, the system can drop the activity
* from memory by either asking it to finish, or simply killing its
* process. When it is displayed again to the user, it must be
* completely restarted and restored to its previous state.</li>
* </ul>
*
* <p>The following diagram shows the important state paths of an Activity.
* The square rectangles represent callback methods you can implement to
* perform operations when the Activity moves between states. The colored
* ovals are major states the Activity can be in.</p>
*
* <p><img src="../../../images/activity_lifecycle.png"
* alt="State diagram for an Android Activity Lifecycle." border="0" /></p>
*
* <p>There are three key loops you may be interested in monitoring within your
* activity:
*
* <ul>
* <li>The <b>entire lifetime</b> of an activity happens between the first call
* to {@link android.app.Activity#onCreate} through to a single final call
* to {@link android.app.Activity#onDestroy}. An activity will do all setup
* of "global" state in onCreate(), and release all remaining resources in
* onDestroy(). For example, if it has a thread running in the background
* to download data from the network, it may create that thread in onCreate()
* and then stop the thread in onDestroy().
*
* <li>The <b>visible lifetime</b> of an activity happens between a call to
* {@link android.app.Activity#onStart} until a corresponding call to
* {@link android.app.Activity#onStop}. During this time the user can see the
* activity on-screen, though it may not be in the foreground and interacting
* with the user. Between these two methods you can maintain resources that
* are needed to show the activity to the user. For example, you can register
* a {@link android.content.BroadcastReceiver} in onStart() to monitor for changes
* that impact your UI, and unregister it in onStop() when the user no
* longer sees what you are displaying. The onStart() and onStop() methods
* can be called multiple times, as the activity becomes visible and hidden
* to the user.
*
* <li>The <b>foreground lifetime</b> of an activity happens between a call to
* {@link android.app.Activity#onResume} until a corresponding call to
* {@link android.app.Activity#onPause}. During this time the activity is
* in front of all other activities and interacting with the user. An activity
* can frequently go between the resumed and paused states -- for example when
* the device goes to sleep, when an activity result is delivered, when a new
* intent is delivered -- so the code in these methods should be fairly
* lightweight.
* </ul>
*
* <p>The entire lifecycle of an activity is defined by the following
* Activity methods. All of these are hooks that you can override
* to do appropriate work when the activity changes state. All
* activities will implement {@link android.app.Activity#onCreate}
* to do their initial setup; many will also implement
* {@link android.app.Activity#onPause} to commit changes to data and
* otherwise prepare to stop interacting with the user. You should always
* call up to your superclass when implementing these methods.</p>
*
* </p>
* <pre class="prettyprint">
* public class Activity extends ApplicationContext {
* protected void onCreate(Bundle savedInstanceState);
*
* protected void onStart();
*
* protected void onRestart();
*
* protected void onResume();
*
* protected void onPause();
*
* protected void onStop();
*
* protected void onDestroy();
* }
* </pre>
*
* <p>In general the movement through an activity's lifecycle looks like
* this:</p>
*
* <table border="2" width="85%" align="center" frame="hsides" rules="rows">
* <colgroup align="left" span="3" />
* <colgroup align="left" />
* <colgroup align="center" />
* <colgroup align="center" />
*
* <thead>
* <tr><th colspan="3">Method</th> <th>Description</th> <th>Killable?</th> <th>Next</th></tr>
* </thead>
*
* <tbody>
* <tr><td colspan="3" align="left" border="0">{@link android.app.Activity#onCreate onCreate()}</td>
* <td>Called when the activity is first created.
* This is where you should do all of your normal static set up:
* create views, bind data to lists, etc. This method also
* provides you with a Bundle containing the activity's previously
* frozen state, if there was one.
* <p>Always followed by <code>onStart()</code>.</td>
* <td align="center">No</td>
* <td align="center"><code>onStart()</code></td>
* </tr>
*
* <tr><td rowspan="5" style="border-left: none; border-right: none;"> </td>
* <td colspan="2" align="left" border="0">{@link android.app.Activity#onRestart onRestart()}</td>
* <td>Called after your activity has been stopped, prior to it being
* started again.
* <p>Always followed by <code>onStart()</code></td>
* <td align="center">No</td>
* <td align="center"><code>onStart()</code></td>
* </tr>
*
* <tr><td colspan="2" align="left" border="0">{@link android.app.Activity#onStart onStart()}</td>
* <td>Called when the activity is becoming visible to the user.
* <p>Followed by <code>onResume()</code> if the activity comes
* to the foreground, or <code>onStop()</code> if it becomes hidden.</td>
* <td align="center">No</td>
* <td align="center"><code>onResume()</code> or <code>onStop()</code></td>
* </tr>
*
* <tr><td rowspan="2" style="border-left: none;"> </td>
* <td align="left" border="0">{@link android.app.Activity#onResume onResume()}</td>
* <td>Called when the activity will start
* interacting with the user. At this point your activity is at
* the top of the activity stack, with user input going to it.
* <p>Always followed by <code>onPause()</code>.</td>
* <td align="center">No</td>
* <td align="center"><code>onPause()</code></td>
* </tr>
*
* <tr><td align="left" border="0">{@link android.app.Activity#onPause onPause()}</td>
* <td>Called when the system is about to start resuming a previous
* activity. This is typically used to commit unsaved changes to
* persistent data, stop animations and other things that may be consuming
* CPU, etc. Implementations of this method must be very quick because
* the next activity will not be resumed until this method returns.
* <p>Followed by either <code>onResume()</code> if the activity
* returns back to the front, or <code>onStop()</code> if it becomes
* invisible to the user.</td>
* <td align="center"><font color="#800000"><strong>Pre-{@link android.os.Build.VERSION_CODES#HONEYCOMB}</strong></font></td>
* <td align="center"><code>onResume()</code> or<br>
* <code>onStop()</code></td>
* </tr>
*
* <tr><td colspan="2" align="left" border="0">{@link android.app.Activity#onStop onStop()}</td>
* <td>Called when the activity is no longer visible to the user, because
* another activity has been resumed and is covering this one. This
* may happen either because a new activity is being started, an existing
* one is being brought in front of this one, or this one is being
* destroyed.
* <p>Followed by either <code>onRestart()</code> if
* this activity is coming back to interact with the user, or
* <code>onDestroy()</code> if this activity is going away.</td>
* <td align="center"><font color="#800000"><strong>Yes</strong></font></td>
* <td align="center"><code>onRestart()</code> or<br>
* <code>onDestroy()</code></td>
* </tr>
*
* <tr><td colspan="3" align="left" border="0">{@link android.app.Activity#onDestroy onDestroy()}</td>
* <td>The final call you receive before your
* activity is destroyed. This can happen either because the
* activity is finishing (someone called {@link Activity#finish} on
* it), or because the system is temporarily destroying this
* instance of the activity to save space. You can distinguish
* between these two scenarios with the {@link
* Activity#isFinishing} method.</td>
* <td align="center"><font color="#800000"><strong>Yes</strong></font></td>
* <td align="center"><em>nothing</em></td>
* </tr>
* </tbody>
* </table>
*
* <p>Note the "Killable" column in the above table -- for those methods that
* are marked as being killable, after that method returns the process hosting the
* activity may be killed by the system <em>at any time</em> without another line
* of its code being executed. Because of this, you should use the
* {@link #onPause} method to write any persistent data (such as user edits)
* to storage. In addition, the method
* {@link #onSaveInstanceState(Bundle)} is called before placing the activity
* in such a background state, allowing you to save away any dynamic instance
* state in your activity into the given Bundle, to be later received in
* {@link #onCreate} if the activity needs to be re-created.
* See the <a href="#ProcessLifecycle">Process Lifecycle</a>
* section for more information on how the lifecycle of a process is tied
* to the activities it is hosting. Note that it is important to save
* persistent data in {@link #onPause} instead of {@link #onSaveInstanceState}
* because the latter is not part of the lifecycle callbacks, so will not
* be called in every situation as described in its documentation.</p>
*
* <p class="note">Be aware that these semantics will change slightly between
* applications targeting platforms starting with {@link android.os.Build.VERSION_CODES#HONEYCOMB}
* vs. those targeting prior platforms. Starting with Honeycomb, an application
* is not in the killable state until its {@link #onStop} has returned. This
* impacts when {@link #onSaveInstanceState(Bundle)} may be called (it may be
* safely called after {@link #onPause()}) and allows an application to safely
* wait until {@link #onStop()} to save persistent state.</p>
*
* <p class="note">For applications targeting platforms starting with
* {@link android.os.Build.VERSION_CODES#P} {@link #onSaveInstanceState(Bundle)}
* will always be called after {@link #onStop}, so an application may safely
* perform fragment transactions in {@link #onStop} and will be able to save
* persistent state later.</p>
*
* <p>For those methods that are not marked as being killable, the activity's
* process will not be killed by the system starting from the time the method
* is called and continuing after it returns. Thus an activity is in the killable
* state, for example, between after <code>onPause()</code> to the start of
* <code>onResume()</code>.</p>
*
* <a name="ConfigurationChanges"></a>
* <h3>Configuration Changes</h3>
*
* <p>If the configuration of the device (as defined by the
* {@link Configuration Resources.Configuration} class) changes,
* then anything displaying a user interface will need to update to match that
* configuration. Because Activity is the primary mechanism for interacting
* with the user, it includes special support for handling configuration
* changes.</p>
*
* <p>Unless you specify otherwise, a configuration change (such as a change
* in screen orientation, language, input devices, etc) will cause your
* current activity to be <em>destroyed</em>, going through the normal activity
* lifecycle process of {@link #onPause},
* {@link #onStop}, and {@link #onDestroy} as appropriate. If the activity
* had been in the foreground or visible to the user, once {@link #onDestroy} is
* called in that instance then a new instance of the activity will be
* created, with whatever savedInstanceState the previous instance had generated
* from {@link #onSaveInstanceState}.</p>
*
* <p>This is done because any application resource,
* including layout files, can change based on any configuration value. Thus
* the only safe way to handle a configuration change is to re-retrieve all
* resources, including layouts, drawables, and strings. Because activities
* must already know how to save their state and re-create themselves from
* that state, this is a convenient way to have an activity restart itself
* with a new configuration.</p>
*
* <p>In some special cases, you may want to bypass restarting of your
* activity based on one or more types of configuration changes. This is
* done with the {@link android.R.attr#configChanges android:configChanges}
* attribute in its manifest. For any types of configuration changes you say
* that you handle there, you will receive a call to your current activity's
* {@link #onConfigurationChanged} method instead of being restarted. If
* a configuration change involves any that you do not handle, however, the
* activity will still be restarted and {@link #onConfigurationChanged}
* will not be called.</p>
*
* <a name="StartingActivities"></a>
* <h3>Starting Activities and Getting Results</h3>
*
* <p>The {@link android.app.Activity#startActivity}
* method is used to start a
* new activity, which will be placed at the top of the activity stack. It
* takes a single argument, an {@link android.content.Intent Intent},
* which describes the activity
* to be executed.</p>
*
* <p>Sometimes you want to get a result back from an activity when it
* ends. For example, you may start an activity that lets the user pick
* a person in a list of contacts; when it ends, it returns the person
* that was selected. To do this, you call the
* {@link android.app.Activity#startActivityForResult(Intent, int)}
* version with a second integer parameter identifying the call. The result
* will come back through your {@link android.app.Activity#onActivityResult}
* method.</p>
*
* <p>When an activity exits, it can call
* {@link android.app.Activity#setResult(int)}
* to return data back to its parent. It must always supply a result code,
* which can be the standard results RESULT_CANCELED, RESULT_OK, or any
* custom values starting at RESULT_FIRST_USER. In addition, it can optionally
* return back an Intent containing any additional data it wants. All of this
* information appears back on the
* parent's <code>Activity.onActivityResult()</code>, along with the integer
* identifier it originally supplied.</p>
*
* <p>If a child activity fails for any reason (such as crashing), the parent
* activity will receive a result with the code RESULT_CANCELED.</p>
*
* <pre class="prettyprint">
* public class MyActivity extends Activity {
* ...
*
* static final int PICK_CONTACT_REQUEST = 0;
*
* public boolean onKeyDown(int keyCode, KeyEvent event) {
* if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
* // When the user center presses, let them pick a contact.
* startActivityForResult(
* new Intent(Intent.ACTION_PICK,
* new Uri("content://contacts")),
* PICK_CONTACT_REQUEST);
* return true;
* }
* return false;
* }
*
* protected void onActivityResult(int requestCode, int resultCode,
* Intent data) {
* if (requestCode == PICK_CONTACT_REQUEST) {
* if (resultCode == RESULT_OK) {
* // A contact was picked. Here we will just display it
* // to the user.
* startActivity(new Intent(Intent.ACTION_VIEW, data));
* }
* }
* }
* }
* </pre>
*
* <a name="SavingPersistentState"></a>
* <h3>Saving Persistent State</h3>
*
* <p>There are generally two kinds of persistent state that an activity
* will deal with: shared document-like data (typically stored in a SQLite
* database using a {@linkplain android.content.ContentProvider content provider})
* and internal state such as user preferences.</p>
*
* <p>For content provider data, we suggest that activities use an
* "edit in place" user model. That is, any edits a user makes are effectively
* made immediately without requiring an additional confirmation step.
* Supporting this model is generally a simple matter of following two rules:</p>
*
* <ul>
* <li> <p>When creating a new document, the backing database entry or file for
* it is created immediately. For example, if the user chooses to write
* a new email, a new entry for that email is created as soon as they
* start entering data, so that if they go to any other activity after
* that point this email will now appear in the list of drafts.</p>
* <li> <p>When an activity's <code>onPause()</code> method is called, it should
* commit to the backing content provider or file any changes the user
* has made. This ensures that those changes will be seen by any other
* activity that is about to run. You will probably want to commit
* your data even more aggressively at key times during your
* activity's lifecycle: for example before starting a new
* activity, before finishing your own activity, when the user
* switches between input fields, etc.</p>
* </ul>
*
* <p>This model is designed to prevent data loss when a user is navigating
* between activities, and allows the system to safely kill an activity (because
* system resources are needed somewhere else) at any time after it has been
* paused. Note this implies
* that the user pressing BACK from your activity does <em>not</em>
* mean "cancel" -- it means to leave the activity with its current contents
* saved away. Canceling edits in an activity must be provided through
* some other mechanism, such as an explicit "revert" or "undo" option.</p>
*
* <p>See the {@linkplain android.content.ContentProvider content package} for
* more information about content providers. These are a key aspect of how
* different activities invoke and propagate data between themselves.</p>
*
* <p>The Activity class also provides an API for managing internal persistent state
* associated with an activity. This can be used, for example, to remember
* the user's preferred initial display in a calendar (day view or week view)
* or the user's default home page in a web browser.</p>
*
* <p>Activity persistent state is managed
* with the method {@link #getPreferences},
* allowing you to retrieve and
* modify a set of name/value pairs associated with the activity. To use
* preferences that are shared across multiple application components
* (activities, receivers, services, providers), you can use the underlying
* {@link Context#getSharedPreferences Context.getSharedPreferences()} method
* to retrieve a preferences
* object stored under a specific name.
* (Note that it is not possible to share settings data across application
* packages -- for that you will need a content provider.)</p>
*
* <p>Here is an excerpt from a calendar activity that stores the user's
* preferred view mode in its persistent settings:</p>
*
* <pre class="prettyprint">
* public class CalendarActivity extends Activity {
* ...
*
* static final int DAY_VIEW_MODE = 0;
* static final int WEEK_VIEW_MODE = 1;
*
* private SharedPreferences mPrefs;
* private int mCurViewMode;
*
* protected void onCreate(Bundle savedInstanceState) {
* super.onCreate(savedInstanceState);
*
* SharedPreferences mPrefs = getSharedPreferences();
* mCurViewMode = mPrefs.getInt("view_mode", DAY_VIEW_MODE);
* }
*
* protected void onPause() {
* super.onPause();
*
* SharedPreferences.Editor ed = mPrefs.edit();
* ed.putInt("view_mode", mCurViewMode);
* ed.commit();
* }
* }
* </pre>
*
* <a name="Permissions"></a>
* <h3>Permissions</h3>
*
* <p>The ability to start a particular Activity can be enforced when it is
* declared in its
* manifest's {@link android.R.styleable#AndroidManifestActivity <activity>}
* tag. By doing so, other applications will need to declare a corresponding
* {@link android.R.styleable#AndroidManifestUsesPermission <uses-permission>}
* element in their own manifest to be able to start that activity.
*
* <p>When starting an Activity you can set {@link Intent#FLAG_GRANT_READ_URI_PERMISSION
* Intent.FLAG_GRANT_READ_URI_PERMISSION} and/or {@link Intent#FLAG_GRANT_WRITE_URI_PERMISSION
* Intent.FLAG_GRANT_WRITE_URI_PERMISSION} on the Intent. This will grant the
* Activity access to the specific URIs in the Intent. Access will remain
* until the Activity has finished (it will remain across the hosting
* process being killed and other temporary destruction). As of
* {@link android.os.Build.VERSION_CODES#GINGERBREAD}, if the Activity
* was already created and a new Intent is being delivered to
* {@link #onNewIntent(Intent)}, any newly granted URI permissions will be added
* to the existing ones it holds.
*
* <p>See the <a href="{@docRoot}guide/topics/security/security.html">Security and Permissions</a>
* document for more information on permissions and security in general.
*
* <a name="ProcessLifecycle"></a>
* <h3>Process Lifecycle</h3>
*
* <p>The Android system attempts to keep an application process around for as
* long as possible, but eventually will need to remove old processes when
* memory runs low. As described in <a href="#ActivityLifecycle">Activity
* Lifecycle</a>, the decision about which process to remove is intimately
* tied to the state of the user's interaction with it. In general, there
* are four states a process can be in based on the activities running in it,
* listed here in order of importance. The system will kill less important
* processes (the last ones) before it resorts to killing more important
* processes (the first ones).
*
* <ol>
* <li> <p>The <b>foreground activity</b> (the activity at the top of the screen
* that the user is currently interacting with) is considered the most important.
* Its process will only be killed as a last resort, if it uses more memory
* than is available on the device. Generally at this point the device has
* reached a memory paging state, so this is required in order to keep the user
* interface responsive.
* <li> <p>A <b>visible activity</b> (an activity that is visible to the user
* but not in the foreground, such as one sitting behind a foreground dialog)
* is considered extremely important and will not be killed unless that is
* required to keep the foreground activity running.
* <li> <p>A <b>background activity</b> (an activity that is not visible to
* the user and has been paused) is no longer critical, so the system may
* safely kill its process to reclaim memory for other foreground or
* visible processes. If its process needs to be killed, when the user navigates
* back to the activity (making it visible on the screen again), its
* {@link #onCreate} method will be called with the savedInstanceState it had previously
* supplied in {@link #onSaveInstanceState} so that it can restart itself in the same
* state as the user last left it.
* <li> <p>An <b>empty process</b> is one hosting no activities or other
* application components (such as {@link Service} or
* {@link android.content.BroadcastReceiver} classes). These are killed very
* quickly by the system as memory becomes low. For this reason, any
* background operation you do outside of an activity must be executed in the
* context of an activity BroadcastReceiver or Service to ensure that the system
* knows it needs to keep your process around.
* </ol>
*
* <p>Sometimes an Activity may need to do a long-running operation that exists
* independently of the activity lifecycle itself. An example may be a camera
* application that allows you to upload a picture to a web site. The upload
* may take a long time, and the application should allow the user to leave
* the application while it is executing. To accomplish this, your Activity
* should start a {@link Service} in which the upload takes place. This allows
* the system to properly prioritize your process (considering it to be more
* important than other non-visible applications) for the duration of the
* upload, independent of whether the original activity is paused, stopped,
* or finished.
*/
public class Activity extends ContextThemeWrapper
implements LayoutInflater.Factory2,
Window.Callback, KeyEvent.Callback,
OnCreateContextMenuListener, ComponentCallbacks2,
Window.OnWindowDismissedCallback, WindowControllerCallback,
AutofillManager.AutofillClient {
private static final String TAG = "Activity";
private static final boolean DEBUG_LIFECYCLE = false;
/** Standard activity result: operation canceled. */
public static final int RESULT_CANCELED = 0;
/** Standard activity result: operation succeeded. */
public static final int RESULT_OK = -1;
/** Start of user-defined activity results. */
public static final int RESULT_FIRST_USER = 1;
/** @hide Task isn't finished when activity is finished */
public static final int DONT_FINISH_TASK_WITH_ACTIVITY = 0;
/**
* @hide Task is finished if the finishing activity is the root of the task. To preserve the
* past behavior the task is also removed from recents.
*/
public static final int FINISH_TASK_WITH_ROOT_ACTIVITY = 1;
/**
* @hide Task is finished along with the finishing activity, but it is not removed from
* recents.
*/
public static final int FINISH_TASK_WITH_ACTIVITY = 2;
static final String FRAGMENTS_TAG = "android:fragments";
private static final String LAST_AUTOFILL_ID = "android:lastAutofillId";
private static final String AUTOFILL_RESET_NEEDED = "@android:autofillResetNeeded";
private static final String WINDOW_HIERARCHY_TAG = "android:viewHierarchyState";
private static final String SAVED_DIALOG_IDS_KEY = "android:savedDialogIds";
private static final String SAVED_DIALOGS_TAG = "android:savedDialogs";
private static final String SAVED_DIALOG_KEY_PREFIX = "android:dialog_";
private static final String SAVED_DIALOG_ARGS_KEY_PREFIX = "android:dialog_args_";
private static final String HAS_CURENT_PERMISSIONS_REQUEST_KEY =
"android:hasCurrentPermissionsRequest";
private static final String REQUEST_PERMISSIONS_WHO_PREFIX = "@android:requestPermissions:";
private static final String AUTO_FILL_AUTH_WHO_PREFIX = "@android:autoFillAuth:";
private static final String KEYBOARD_SHORTCUTS_RECEIVER_PKG_NAME = "com.android.systemui";
private static final int LOG_AM_ON_CREATE_CALLED = 30057;
private static final int LOG_AM_ON_START_CALLED = 30059;
private static final int LOG_AM_ON_RESUME_CALLED = 30022;
private static final int LOG_AM_ON_PAUSE_CALLED = 30021;
private static final int LOG_AM_ON_STOP_CALLED = 30049;
private static final int LOG_AM_ON_RESTART_CALLED = 30058;
private static final int LOG_AM_ON_DESTROY_CALLED = 30060;
private static final int LOG_AM_ON_ACTIVITY_RESULT_CALLED = 30062;
private static class ManagedDialog {
Dialog mDialog;
Bundle mArgs;
}
private SparseArray<ManagedDialog> mManagedDialogs;
// set by the thread after the constructor and before onCreate(Bundle savedInstanceState) is called.
private Instrumentation mInstrumentation;
private IBinder mToken;
private int mIdent;
/*package*/ String mEmbeddedID;
private Application mApplication;
/*package*/ Intent mIntent;
/*package*/ String mReferrer;
private ComponentName mComponent;
/*package*/ ActivityInfo mActivityInfo;
/*package*/ ActivityThread mMainThread;
Activity mParent;
boolean mCalled;
/*package*/ boolean mResumed;
/*package*/ boolean mStopped;
boolean mFinished;
boolean mStartedActivity;
private boolean mDestroyed;
private boolean mDoReportFullyDrawn = true;
private boolean mRestoredFromBundle;
/** {@code true} if the activity lifecycle is in a state which supports picture-in-picture.
* This only affects the client-side exception, the actual state check still happens in AMS. */
private boolean mCanEnterPictureInPicture = false;
/** true if the activity is going through a transient pause */
/*package*/ boolean mTemporaryPause = false;
/** true if the activity is being destroyed in order to recreate it with a new configuration */
/*package*/ boolean mChangingConfigurations = false;
/*package*/ int mConfigChangeFlags;
/*package*/ Configuration mCurrentConfig;
private SearchManager mSearchManager;
private MenuInflater mMenuInflater;
/** The autofill manager. Always access via {@link #getAutofillManager()}. */
@Nullable private AutofillManager mAutofillManager;
static final class NonConfigurationInstances {
Object activity;
HashMap<String, Object> children;
FragmentManagerNonConfig fragments;
ArrayMap<String, LoaderManager> loaders;
VoiceInteractor voiceInteractor;
}
/* package */ NonConfigurationInstances mLastNonConfigurationInstances;
private Window mWindow;
private WindowManager mWindowManager;
/*package*/ View mDecor = null;
/*package*/ boolean mWindowAdded = false;
/*package*/ boolean mVisibleFromServer = false;
/*package*/ boolean mVisibleFromClient = true;
/*package*/ ActionBar mActionBar = null;
private boolean mEnableDefaultActionBarUp;
private VoiceInteractor mVoiceInteractor;
private CharSequence mTitle;
private int mTitleColor = 0;
// we must have a handler before the FragmentController is constructed
final Handler mHandler = new Handler();
final FragmentController mFragments = FragmentController.createController(new HostCallbacks());
private static final class ManagedCursor {
ManagedCursor(Cursor cursor) {
mCursor = cursor;
mReleased = false;
mUpdated = false;
}
private final Cursor mCursor;
private boolean mReleased;
private boolean mUpdated;
}
@GuardedBy("mManagedCursors")
private final ArrayList<ManagedCursor> mManagedCursors = new ArrayList<>();
@GuardedBy("this")
int mResultCode = RESULT_CANCELED;
@GuardedBy("this")
Intent mResultData = null;
private TranslucentConversionListener mTranslucentCallback;
private boolean mChangeCanvasToTranslucent;
private SearchEvent mSearchEvent;
private boolean mTitleReady = false;
private int mActionModeTypeStarting = ActionMode.TYPE_PRIMARY;
private int mDefaultKeyMode = DEFAULT_KEYS_DISABLE;
private SpannableStringBuilder mDefaultKeySsb = null;
private ActivityManager.TaskDescription mTaskDescription =
new ActivityManager.TaskDescription();
protected static final int[] FOCUSED_STATE_SET = {com.android.internal.R.attr.state_focused};
@SuppressWarnings("unused")
private final Object mInstanceTracker = StrictMode.trackActivity(this);
private Thread mUiThread;
ActivityTransitionState mActivityTransitionState = new ActivityTransitionState();
SharedElementCallback mEnterTransitionListener = SharedElementCallback.NULL_CALLBACK;
SharedElementCallback mExitTransitionListener = SharedElementCallback.NULL_CALLBACK;
private boolean mHasCurrentPermissionsRequest;
private boolean mAutoFillResetNeeded;
private boolean mAutoFillIgnoreFirstResumePause;
/** The last autofill id that was returned from {@link #getNextAutofillId()} */
private int mLastAutofillId = View.LAST_APP_AUTOFILL_ID;
private AutofillPopupWindow mAutofillPopupWindow;
private static native String getDlWarning();
/** Return the intent that started this activity. */
public Intent getIntent() {
return mIntent;
}
/**
* Change the intent returned by {@link #getIntent}. This holds a
* reference to the given intent; it does not copy it. Often used in
* conjunction with {@link #onNewIntent}.
*
* @param newIntent The new Intent object to return from getIntent
*
* @see #getIntent
* @see #onNewIntent
*/
public void setIntent(Intent newIntent) {
mIntent = newIntent;
}
/** Return the application that owns this activity. */
public final Application getApplication() {
return mApplication;
}
/** Is this activity embedded inside of another activity? */
public final boolean isChild() {
return mParent != null;
}
/** Return the parent activity if this view is an embedded child. */
public final Activity getParent() {
return mParent;
}
/** Retrieve the window manager for showing custom windows. */
public WindowManager getWindowManager() {
return mWindowManager;
}
/**
* Retrieve the current {@link android.view.Window} for the activity.
* This can be used to directly access parts of the Window API that
* are not available through Activity/Screen.
*
* @return Window The current window, or null if the activity is not
* visual.
*/
public Window getWindow() {
return mWindow;
}
/**
* Return the LoaderManager for this activity, creating it if needed.
*
* @deprecated Use {@link android.support.v4.app.FragmentActivity#getSupportLoaderManager()}
*/
@Deprecated
public LoaderManager getLoaderManager() {
return mFragments.getLoaderManager();
}
/**
* Calls {@link android.view.Window#getCurrentFocus} on the
* Window of this Activity to return the currently focused view.
*
* @return View The current View with focus or null.
*
* @see #getWindow
* @see android.view.Window#getCurrentFocus
*/
@Nullable
public View getCurrentFocus() {
return mWindow != null ? mWindow.getCurrentFocus() : null;
}
/**
* (Create and) return the autofill manager
*
* @return The autofill manager
*/
@NonNull private AutofillManager getAutofillManager() {
if (mAutofillManager == null) {
mAutofillManager = getSystemService(AutofillManager.class);
}
return mAutofillManager;
}
@Override
protected void attachBaseContext(Context newBase) {
super.attachBaseContext(newBase);
if (newBase != null) {
newBase.setAutofillClient(this);
}
}
/** @hide */
@Override
public final AutofillClient getAutofillClient() {
return this;
}
/**
* Called when the activity is starting. This is where most initialization
* should go: calling {@link #setContentView(int)} to inflate the
* activity's UI, using {@link #findViewById} to programmatically interact
* with widgets in the UI, calling
* {@link #managedQuery(android.net.Uri , String[], String, String[], String)} to retrieve
* cursors for data being displayed, etc.
*