UI Thread'ine yaptırmak için nasıl iş planlanır? runOnUIThread, post, AsyncTask ve Handler&Looper kullanımı

1. Android Thread Modeli
Murat Can ALPAY
v1.0

2. Murat Can ALPAY
linkedin.com/in/mcalpay
mcatr.blogspot.com

3. İçerik
● Tekil Thread Modeli
● Uzun süreli görevler
● Thread API

4. Kime Yönelik
● Yeni Başlayan
● Thread ve örüntüleri

5. Tekil Thread Modeli
UI Thread
DrawHandle
Events
Resume
Activities

6. Problem 1
btnSave.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
saveInternalStorage();
}
});

7. Problem 1
btnSave.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
saveInternalStorage();
synchronizeOnWeb(); // long running operation,
// or Thread.sleep(...
}
});

8. Tekil Thread Modeli
UI Thread
DrawHandle
Events
Resume
Activities

9. Tekil Thread Modeli
● Tüm GUI çatıları tekil thread modeli
kullanıyor.

10. Çoklu Thread Modeli Mümkün mü?
From Brian Goetz's
"Java Concurrency in Practice" Book
9.1 Why are GUIs single-threaded?
Single-threaded GUI frameworks are not unique to Java; Qt, NextStep,
MacOS Cocoa, X Windows, and many others are also single-threaded. This
is not for lack of trying; there have been many attempts to write
multithreaded GUI frameworks, but because of persistent problems with
race conditions and deadlock...
UI Thread UI ThreadUI ThreadUI Thread
UI Thread

11. Problem 1
btnSave.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
saveInternalStorage();
synchronizeOnWeb(); // long running operation,
// or Thread.sleep(2000)
}
});

12. Solution 1
btnSave.setOnClickListener(new OnClickListener() {
@Override public void onClick(View v) {
new Thread(new Runnable() {
@Override
public void run() {
longRunningOperation();
}
}).start();
}
});

13. İlerlemeyi Görünür Kıl

14. Problem 2
public void onClick(View v) {
new Thread(new Runnable() {
public void run() {
...
btnSave.setImageResource(R.drawable.progress1);
...
}
}).start();
}

15. Problem 2
android.view.ViewRootImpl$CalledFromWrongThreadException:
Only the original thread that created a view hierarchy can touch its views.
at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4746)
...
at android.widget.ImageView.setImageResource(ImageView.java:352)
at mca.activities.NoteListActivity$3$1.run(NoteListActivity.java:69)
at java.lang.Thread.run(Thread.java:856)

16. Thread Safe
Brian Goetz "Java Concurrency in Practice"
"A class is thread-safe if it behaves correctly when accessed
from multiple threads, regardless of the scheduling or
interleaving of the execution of those threads by the
runtime environment, and with no additional
synchronization or other coordination on the part of the
calling code."

17. Thread API
● android.app.Activity.runOnUiThread(Runnable)
● android.view.View.post(Runnable)
● android.os.AsyncTask

18. runOnUiThread vs. post
● küçük farklılık?
● Şu anki thread UI thread'i ise Runnable çalıştırılır
değilse mesaj kuyruğuna eklenir.
● Runnable'ın UI Thread'inin mesaj kuyruğuna
eklenmesini sağlar.

19. Solution 2.1
public void onClick(View v) {
new Thread(new Runnable() {
public void run() {
NoteListActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
btnTest.setImageResource(R.drawable.progress1);
}
});
}
}).start();
}

20. Solution 2.2
public void onClick(View v) {
new Thread(new Runnable() {
public void run() {
btnTest.post(new Runnable() {
@Override
public void run() {
btnTest.setImageResource(R.drawable.progress1);
}
});
}
}).start();
}

21. İlerlemeyi Görünür Kıl

22. Solution 3
final ProgressControllerAnimationThread progressT =
new ProgressControllerAnimationThread(btnSave,
R.drawable.save);
progressT.start();
new Thread(new Runnable() {
@Override
public void run() {
...
boolean result = longRunningOperation();
progressT.end(result);
}
}).start();

23. AsyncTask
● android.os.AsyncTask<Params, Progress, Result>
● execute()

24. AsyncTask
● onPreExecute()
● doInBackground(Params...)
○ publishProgress(Progress...)
● onProgressUpdate(Progress...)
● onPostExecute(Result)

25. AsyncTask
public void onClick(View v) {
AsyncTask<Void, Integer, Void> testTask = new AsyncTask...{
protected Void doInBackground(Void... params) {
...
while (!opComplete()) {
doApartOfLongRunningOp();
if (System.currentTimeMillis() - changeTime > 100) {
changeTime = System.currentTimeMillis();
publishProgress(progress++);
}
}
return null;
}
protected void onProgressUpdate(Integer... values) {...}
};
testTask.execute();
}

26. android.os.(Handler & Looper)
● Thread için mesaj kuyruğu
● Handler
○ handleMessage
○ sendMessage
○ post

27. Handler & Looper
// Looper is already defined for UI Thread
handler = new Handler() {
public void handleMessage(Message msg) {
btnSave.setImageResource(R.drawable.add);}};
btnSave.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
new Thread(new Runnable() {
public void run() {...
handler.sendMessage(new Message());}
}).start();
}});

28. android.os.(Handler & Looper)
● Looper
○ prepare
○ loop
● Thread.run metodu içinde çalışmalı

29. Thread Öncelikleri
● Arkaplan threadleri çok daha az öncelikle çalışıyor

30. Özet
● Kullanıcı deneyimi
● Tekil Thread Modeli
● 3 metot
○ post
○ runOnUIThread
○ AsyncTask

31. Teşekkürler
?