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![Support library can be upgraded!
24
dependencies
{
compile
'com.android.support:appcompat-‐v7:+'
compile
'com.android.support:support-‐v4:19.1.+'
compile
fileTree(dir:
'libs',
include:
['*.jar'])
}](https://image.slidesharecdn.com/androidprogramming-pushingthelimits-droidconde2014-clean-140609162610-phpapp01/85/Android-programming-_pushing_the_limits-24-320.jpg)
![Most common ContentProvider mistake :)
32
@Override
public
Cursor
query(Uri
uri,
String[]
projection,
String
selection,
String[]
selectionArgs,
String
sortOrder)
{
SQLiteDatabase
db
=
mDatabaseHelper.getReadableDatabase();
int
match
=
sUriMatcher.match(uri);
Cursor
cursor
=
null;
switch
(match)
{
case
ALL_ROWS:
cursor
=
db.query(Contract.TABLE_NAME,
projection,
selection,
selectionArgs,
"",
"",
sortOrder);
break;
case
SINGLE_ROW:
String
id
=
uri.getLastPathSegment();
cursor
=
db.query(Contract.TABLE_NAME,
projection,
"_id
=
?",
new
String[]{id},
"",
"",
sortOrder);
break;
}
if(cursor
!=
null)
{
cursor.setNotificationUri(getContext().getContentResolver(),
uri);
}
return
cursor;
}](https://image.slidesharecdn.com/androidprogramming-pushingthelimits-droidconde2014-clean-140609162610-phpapp01/85/Android-programming-_pushing_the_limits-32-320.jpg)
![Don’t forget bulkInsert() !!!
34
@Override
public
int
bulkInsert(Uri
uri,
ContentValues[]
values)
{
SQLiteDatabase
db
=
mDatabaseHelper.getWritableDatabase();
int
match
=
sUriMatcher.match(uri);
int
inserted
=
0;
switch
(match)
{
case
TASKS_CODE:
try
{
db.beginTransaction();
for
(ContentValues
value
:
values)
{
long
id
=
db.insert(Contract.TABLE_NAME,
"",
value);
if
(id
<=
0)
throw
new
SQLException("Failed
with
inserting.");
inserted++;
}
db.setTransactionSuccessful();
getContext().getContentResolver().notifyChange(uri,
null);
}
finally
{
db.endTransaction();
}
}
return
inserted;
}](https://image.slidesharecdn.com/androidprogramming-pushingthelimits-droidconde2014-clean-140609162610-phpapp01/85/Android-programming-_pushing_the_limits-34-320.jpg)
![Support library can be upgraded!
24
dependencies
{
compile
'com.android.support:appcompat-‐v7:+'
compile
'com.android.support:support-‐v4:19.1.+'
compile
fileTree(dir:
'libs',
include:
['*.jar'])
}](https://image.slidesharecdn.com/androidprogramming-pushingthelimits-droidconde2014-clean-140609162610-phpapp01/75/Android-programming-_pushing_the_limits-24-2048.jpg)
![Most common ContentProvider mistake :)
32
@Override
public
Cursor
query(Uri
uri,
String[]
projection,
String
selection,
String[]
selectionArgs,
String
sortOrder)
{
SQLiteDatabase
db
=
mDatabaseHelper.getReadableDatabase();
int
match
=
sUriMatcher.match(uri);
Cursor
cursor
=
null;
switch
(match)
{
case
ALL_ROWS:
cursor
=
db.query(Contract.TABLE_NAME,
projection,
selection,
selectionArgs,
"",
"",
sortOrder);
break;
case
SINGLE_ROW:
String
id
=
uri.getLastPathSegment();
cursor
=
db.query(Contract.TABLE_NAME,
projection,
"_id
=
?",
new
String[]{id},
"",
"",
sortOrder);
break;
}
if(cursor
!=
null)
{
cursor.setNotificationUri(getContext().getContentResolver(),
uri);
}
return
cursor;
}](https://image.slidesharecdn.com/androidprogramming-pushingthelimits-droidconde2014-clean-140609162610-phpapp01/75/Android-programming-_pushing_the_limits-32-2048.jpg)
![Don’t forget bulkInsert() !!!
34
@Override
public
int
bulkInsert(Uri
uri,
ContentValues[]
values)
{
SQLiteDatabase
db
=
mDatabaseHelper.getWritableDatabase();
int
match
=
sUriMatcher.match(uri);
int
inserted
=
0;
switch
(match)
{
case
TASKS_CODE:
try
{
db.beginTransaction();
for
(ContentValues
value
:
values)
{
long
id
=
db.insert(Contract.TABLE_NAME,
"",
value);
if
(id
<=
0)
throw
new
SQLException("Failed
with
inserting.");
inserted++;
}
db.setTransactionSuccessful();
getContext().getContentResolver().notifyChange(uri,
null);
}
finally
{
db.endTransaction();
}
}
return
inserted;
}](https://image.slidesharecdn.com/androidprogramming-pushingthelimits-droidconde2014-clean-140609162610-phpapp01/75/Android-programming-_pushing_the_limits-34-2048.jpg)
Uploaded byDroidcon Berlin
Android programming -_pushing_the_limits
This document discusses techniques for improving Android application performance, including: 1. Using static factory methods and object pooling to improve memory management. 2. Configuring applications and services to run in separate processes to improve isolation and increase available memory. 3. Implementing multi-threading correctly using Handlers to schedule work off the UI thread and reduce garbage collection calls. 4. Understanding how to use Android application and activity components like Services and Fragments appropriately.
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Android programming -_pushing_the_limits
- 1. Pushing the Limits ErikHellman, Spotify google.com/+ErikHellman @ErikHellman Android Programming
- 2.
- 3. 3 Improved memory management Efficientmulti-threading and -processing Using Android components correctly
- 4.
- 5. Use a staticfactory method whenever possible 5 Effective Java (2nd ed.): Item 1! “A second advantage of static factory methods is that, unlike constructors, they are not required to create a new object each time they’re invoked.”
- 6. Message.java 6 public final class Message implements Parcelable { /*package*/ Message next; ! private static final Object sPoolSync = new Object(); private static Message sPool; private static int sPoolSize = 0; ! private static final int MAX_POOL_SIZE = 50; ! public static Message obtain() { synchronized (sPoolSync) { if (sPool != null) { Message m = sPool; sPool = m.next; m.next = null; sPoolSize-‐-‐; return m; } } return new Message(); } public void recycle() { clearForRecycle(); ! synchronized (sPoolSync) { if (sPoolSize < MAX_POOL_SIZE) { next = sPool; sPool = this; sPoolSize++; } } } }
- 7. How to getmore memory - Part 1 7 <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:name=".MyApplication" android:largeHeap="true" android:theme="@style/AppTheme" > … </application>
- 8. How to getmore memory - Part 2 8 <service android:name="se.hellsoft.apptl.app.MyService" android:enabled="true" android:exported="false" android:process="se.hellsoft.apptl.service"> </service>
- 9. How to getmore memory - Part 3 9 data = malloc(sizeof(data_struct));
- 10. 10 Improved memory management Efficientmulti-threading and -processing Using Android components correctly
- 11. 11 Always use aHandler!* * Except when you shouldn’t… @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); HandlerThread backgroundThread = new HandlerThread("background"); backgroundThread.start(); mBackgroundHandler = new Handler(backgroundThread.getLooper(), this); mUiHandler = new Handler(this); } ! @Override protected void onDestroy() { super.onDestroy(); mBackgroundHandler.removeCallbacksAndMessages(null); mBackgroundHandler.getLooper().quit(); }
- 12. 12 Always use aHandler!* * Except when you shouldn’t… public void onStartBackgroundJob(View view) { mBackgroundHandler.obtainMessage(BACKGROUND_JOB).sendToTarget(); } ! @Override public boolean handleMessage(Message msg) { switch (msg.what) { case BACKGROUND_JOB: Bitmap result = null; // Processing goes here... mUiHandler.obtainMessage(UPDATE_UI, result).sendToTarget(); break; case UPDATE_UI: ((ImageView) findViewById(R.id.photo)) .setImageBitmap((Bitmap) msg.obj); break; } return true; }
- 13. Why Handler? 13 •Scheduling ofmessages •Cancelling of messages •Reduces GC calls
- 14. Using the processattribute 14
- 15. Why a separateprocess? 15 •Better isolation from crashes •Binder transactions uses a thread pool •Double the memory!
- 16. 16 Improved memory management Efficientmulti-threading and -processing Using Android components correctly
- 17. Application component 17 <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:name=“.MyApplication" android:theme="@style/AppTheme" > ! ... </application>
- 18. Android Singletons usingContext 18 public class MySingleton { private static MySingleton sInstance; private Context mContext; ! private MySingleton(Context context) { mContext = context; } public MySingleton getInstance(Context context) { if(sInstance == null) { sInstance = new MySingleton(context.getApplicationContext()); } return sInstance; } public void doStuffThatRequireContext() { // Do stuff here... } }
- 19. Application Context limitations 19 •Inflatinglayout uses default theme •Starting Activity creates a new task
- 20. 20 Activity - savingstate Activity.onSaveInstanceState() Activity.onPause() or
- 21. 21 onSaveInstanceState() is notcalled… •…when user presses back •…when you call Activity.finish()
- 22.
- 23.
- 24. Support library canbe upgraded! 24 dependencies { compile 'com.android.support:appcompat-‐v7:+' compile 'com.android.support:support-‐v4:19.1.+' compile fileTree(dir: 'libs', include: ['*.jar']) }
- 25. Typical Fragment crash 25 public static class FirstFragment extends Fragment { private ImageView mImageView; ! @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); mImageView = (ImageView) rootView.findViewById(R.id.photo); ! new AsyncTask<Void, Void, Bitmap>() { @Override protected Bitmap doInBackground(Void... params) { SystemClock.sleep(10000); // Fake long processing... return BitmapFactory.decodeResource(getResources(), R.drawable.happy_android); } ! @Override protected void onPostExecute(Bitmap bitmap) { mImageView.setImageBitmap(bitmap); } }.execute(); ! return rootView; } }
- 26. Typical Fragment crash 26 E/AndroidRuntime( 1245): FATAL EXCEPTION: AsyncTask #1 E/AndroidRuntime( 1245): Process: se.hellsoft.apptl.app, PID: 1245 E/AndroidRuntime( 1245): java.lang.RuntimeException: An error occured while executing doInBackground() E/AndroidRuntime( 1245): at android.os.AsyncTask$3.done(AsyncTask.java:300) E/AndroidRuntime( 1245): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) E/AndroidRuntime( 1245): at java.util.concurrent.FutureTask.setException(FutureTask.java:222) E/AndroidRuntime( 1245): at java.util.concurrent.FutureTask.run(FutureTask.java:242) E/AndroidRuntime( 1245): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) E/AndroidRuntime( 1245): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) E/AndroidRuntime( 1245): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) E/AndroidRuntime( 1245): at java.lang.Thread.run(Thread.java:841) E/AndroidRuntime( 1245): Caused by: java.lang.IllegalStateException: Fragment FirstFragment{52836468} not attached to Activity E/AndroidRuntime( 1245): at android.support.v4.app.Fragment.getResources(Fragment.java:601) E/AndroidRuntime( 1245): at se.hellsoft.apptl.app.MainActivity$FirstFragment $1.doInBackground(MainActivity.java:115) E/AndroidRuntime( 1245): at se.hellsoft.apptl.app.MainActivity$FirstFragment $1.doInBackground(MainActivity.java:109) E/AndroidRuntime( 1245): at android.os.AsyncTask$2.call(AsyncTask.java:288) E/AndroidRuntime( 1245): at java.util.concurrent.FutureTask.run(FutureTask.java:237) E/AndroidRuntime( 1245): ... 4 more
- 27. 27 Use a Loaderwhenever possible and cancel remaining requests in onPause()/onDetach()!
- 28. Binding to Services 28 @Override public IBinder onBind(Intent intent) { return null; // NEVER do this }
- 29. Binding to Services 29 @Override public IBinder onBind(Intent intent) { String action = intent.getAction(); if(ACTION_FIRST_BINDER.equals(action)) { return mFirstBinder; } else if(ACTION_SECOND_BINDER.equals(action)) { return mSecondBinder; } else { throw new RuntimeException("Unexpected error!"); } }
- 30. Binding to Services 30 @Override public IBinder onBind(Intent intent) { Uri data = intent.getData(); String param = data.getQueryParameter("param"); if(FIRST_BINDER.equals(param)) { return mFirstBinder; } else if(SECOND_BINDER.equals(param)) { return mSecondBinder; } else { throw new RuntimeException("Unexpected error!:"); } }
- 31. Service considerations 31 •A binderIntent is identified by the action string and data Uri! ! •onBind() and onUnbind() only called once per unique Intent •START_STICKY will give a null Intent when Service is restarted by the system •Binder calls run on local thread for process-local service
- 32. Most common ContentProvidermistake :) 32 @Override public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { SQLiteDatabase db = mDatabaseHelper.getReadableDatabase(); int match = sUriMatcher.match(uri); Cursor cursor = null; switch (match) { case ALL_ROWS: cursor = db.query(Contract.TABLE_NAME, projection, selection, selectionArgs, "", "", sortOrder); break; case SINGLE_ROW: String id = uri.getLastPathSegment(); cursor = db.query(Contract.TABLE_NAME, projection, "_id = ?", new String[]{id}, "", "", sortOrder); break; } if(cursor != null) { cursor.setNotificationUri(getContext().getContentResolver(), uri); } return cursor; }
- 33. Most common ContentProvidermistake :) 33 @Override public Uri insert(Uri uri, ContentValues values) { SQLiteDatabase db = mDatabaseHelper.getWritableDatabase(); int match = sUriMatcher.match(uri); switch (match) { case ALL_ROWS: long newId = db.insert(Contract.TABLE_NAME, "", values); if(newId != -‐1) { getContext().getContentResolver().notifyChange(uri, null); } return Uri.withAppendedPath(uri, String.valueOf(newId)); default: return null; } }
- 34. Don’t forget bulkInsert()!!! 34 @Override public int bulkInsert(Uri uri, ContentValues[] values) { SQLiteDatabase db = mDatabaseHelper.getWritableDatabase(); int match = sUriMatcher.match(uri); int inserted = 0; switch (match) { case TASKS_CODE: try { db.beginTransaction(); for (ContentValues value : values) { long id = db.insert(Contract.TABLE_NAME, "", value); if (id <= 0) throw new SQLException("Failed with inserting."); inserted++; } db.setTransactionSuccessful(); getContext().getContentResolver().notifyChange(uri, null); } finally { db.endTransaction(); } } return inserted; }
- 35. Useful Broadcasts -Auto-starting 35 <receiver android:name="se.hellsoft.myapp.AutoStartReceiver" > <intent-‐filter> <action android:name="android.intent.action.BOOT_COMPLETED" /> </intent-‐filter> </receiver> <receiver android:name=“se.hellsoft.myapp.AutoStartReceiver" android:process=“:autostarter”> <intent-‐filter> <action android:name="android.intent.action.USER_PRESENT" /> </intent-‐filter> </receiver>
- 36. Useful Broadcasts -Monitoring the network 36 <receiver android:name=“se.hellsoft.myapp.NetworkMonitor"> <intent-‐filter> <action android:name="android.net.conn.CONNECTIVITY_CHANGE" /> <action android:name="android.net.wifi.supplicant.CONNECTION_CHANGE" /> <action android:name="android.net.wifi.WIFI_AP_STATE_CHANGED" /> </intent-‐filter> </receiver>
- 37. 37 “Many problems withAndroid apps can be fixed with a proper use of the Handler class.” - Erik Hellman Get my book at wiley.com/go/ptl/androidprogramming