I want to save data to DB in new Thread and after that show toast on the UI.
Method for saving:
public void addToBasket(String text) {
new Thread(() -> {
//emulate save
try {
Thread.sleep(5000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
//after that I need say ti UI thread - show Toast!
}).start();
}
I call this method:
BasketService.me().addToBasket(result.getContents());
I do now want use AsyncTask for this. Please tell me the best way to implement such tasks
batter to use:
runOnUiThread(new Runnable() {
public void run() {
//Do what ever you want do man
}
});
runOnUiThread() method to manipulate your UserInterface from background threads.
In case of callback from a nonUi thread to Ui thread you can use runOnUiThread()(As specified above) or Handler. Below is a example of using handler.
protected static final Handler mainThreadHandler = new Handler(Looper.getMainLooper());
protected void onSuccessInMainThread(final R result, final Bundle bundle) {
mainThreadHandler.post(new Runnable() {
#Override
public void run() {
callback.onSuccess(result, bundle);
}
});
}
protected void onErrorInMainThread(final Exception error) {
mainThreadHandler.post(new Runnable() {
#Override
public void run() {
callback.onError(error);
}
});
}
Android recommend update ui in the ui thread,but i found that i can update the ui in the non-ui thread directly like below:
public class MainActivity extends Activity {
private TextView textView;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.text);
new Thread(new Runnable() {
#Override
public void run() {
textView.setText("SecondThread");
}
}).start();
}
}
That's run correctly,but if i sleep the thread 1000ms:
public class MainActivity extends Activity {
private TextView textView;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.text);
new Thread(new Runnable() {
#Override
public void run() {
try {
**Thread.sleep(1000);**
} catch (InterruptedException e) {
e.printStackTrace();
}
textView.setText("SecondThread");
}
}).start();
}
}
I get the error"Only the original thread that created a view hierarchy can touch its views",i try to change the sleep value much times,i found when i set the value 135 or less,it can run correctly：
Thread.sleep(135);
Thread.sleep(134);
Thread.sleep(...);
That's very interesting!But why it happen?I can't find any way to make sense of that,is anyone can help me?thanks!
If you are trying to touch views from background thread you should consider using runOnUiThread method, which accepts runnable as argument in which you can update views
EDIT: Also I would recommed you to use AsyncTask to achieve your goals, it has two callbacks onPreExecute and onPostExecute, whiche are invoked on the UI thread
so will always work
new Thread(new Runnable() {
#Override
public void run() {
try {
**Thread.sleep(1000);**
} catch (InterruptedException e) {
e.printStackTrace();
}
runOnUiThread(new Runable(){
#Override
public void run(){
textView.setText("SecondThread");
});
}
}).start();
There is another way to use the Handler()
Where timer is a textview and throws error during runtime and UI comes out saying unfortunately has stopped.Have attached error mess link below.Plz help not understanding where I am going wrong
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.level_twolayout);
Thread t1 = new Thread(new Runnable() {
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(1000);
} catch (Exception e) {
}
Timer.setText("Hello");
}
}
});
t1.start();
}
You must update UI from main thread.
Use this code. in place of Timer.setText("Hello");
// verify we are indeed updating UI on main thread.
runOnUiThread(new Runnable() {
#Override
public void run() {
// go ahead and update UI
Timer.setText("Hello");
}
});
runOnUiThread is an Activity method. See http://developer.android.com/reference/android/app/Activity.html#runOnUiThread%28java.lang.Runnable%29.
You need to call MyActivityName.this.runOnUiThread() or more simply just runOnUiThread() as "this" will point to the scope of the Runnable you are creating and not your Activity.
Lastly, "Timer" may not be the best name for your TextView.
I have a SetContentView(R.layout.camera);
I want this layout to be start executing after some milliseconds....till then it should be blank. How can I achieve this in android?
For this Write your onCreate() like this..Then it will work..
Thread t = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
t = new Thread(new Runnable() {
#Override
public void run() {
try {
t.sleep(5000);
runOnUiThread(new Runnable() {
public void run() {
setContentView(R.layout.activity_main);
}
});
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
t.start();
}
you can use handler for make delay
Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
//setcontentview
}
};
in oncreate methode
Message m = Message.obtainMessage();
handler.sendMessageDelayed(m, delayMillis);
Your activity will not be visible unless onResume() will get called, Do some operation in main Thread or onCreate() Method it will block your main thread and UI will not be displayed until your operation gets completed.
Create root View with all the components and visibility set to INVISIBLE or GONE and then show it after delay. You can use Handler and postDelayed to execute a code after delay.
I'm trying to use the UI-Thread, so I've written a simple test activity. But I think I've misunderstood something, because on clicking the button - the app does not respond anymore
public class TestActivity extends Activity {
Button btn;
int i = 0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btn = (Button)findViewById(R.id.btn);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
runThread();
}
});
}
private void runThread(){
runOnUiThread (new Thread(new Runnable() {
public void run() {
while(i++ < 1000){
btn.setText("#"+i);
try {
Thread.sleep(300);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}));
}
}
Below is corrected Snippet of runThread Function.
private void runThread() {
new Thread() {
public void run() {
while (i++ < 1000) {
try {
runOnUiThread(new Runnable() {
#Override
public void run() {
btn.setText("#" + i);
}
});
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}.start();
}
Just wrap it as a function, then call this function from your background thread.
public void debugMsg(String msg) {
final String str = msg;
runOnUiThread(new Runnable() {
#Override
public void run() {
mInfo.setText(str);
}
});
}
You have it back-to-front. Your button click results in a call to runOnUiThread(), but this isn't needed, since the click handler is already running on the UI thread. Then, your code in runOnUiThread() is launching a new background thread, where you try to do UI operations, which then fail.
Instead, just launch the background thread directly from your click handler. Then, wrap the calls to btn.setText() inside a call to runOnUiThread().
runOnUiThread(new Runnable() {
public void run() {
//Do something on UiThread
}
});
There are several techniques using of runOnUiThread(), lets see all
This is my main thread (UI thread) called AndroidBasicThreadActivity and I'm going to update it from a worker thread in various ways -
public class AndroidBasicThreadActivity extends AppCompatActivity
{
public static TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_android_basic_thread);
textView = (TextView) findViewById(R.id.textview);
MyAndroidThread myTask = new MyAndroidThread(AndroidBasicThreadActivity.this);
Thread t1 = new Thread(myTask, "Bajrang");
t1.start();
}
}
1.) By passing Activity's instance as an argument on worker thread
class MyAndroidThread implements Runnable
{
Activity activity;
public MyAndroidThread(Activity activity)
{
this.activity = activity;
}
#Override
public void run()
{
//perform heavy task here and finally update the UI with result this way -
activity.runOnUiThread(new Runnable()
{
#Override
public void run()
{
AndroidBasicThreadActivity.textView.setText("Hello!! Android Team :-) From child thread.");
}
});
}
}
2.) By using View's post(Runnable runnable) method in worker thread
class MyAndroidThread implements Runnable
{
Activity activity;
public MyAndroidThread(Activity activity)
{
this.activity = activity;
}
#Override
public void run()
{
//perform heavy task here and finally update the UI with result this way -
AndroidBasicThreadActivity.textView.post(new Runnable()
{
#Override
public void run()
{
AndroidBasicThreadActivity.textView.setText("Hello!! Android Team :-) From child thread.");
}
});
}
}
3.) By using Handler class from android.os package
If we don't have the context (this/ getApplicationContext()) or Activity's instance (AndroidBasicThreadActivity.this) then we have to use Handler class as below -
class MyAndroidThread implements Runnable
{
Activity activity;
public MyAndroidThread(Activity activity)
{
this.activity = activity;
}
#Override
public void run()
{
//perform heavy task here and finally update the UI with result this way -
new Handler(Looper.getMainLooper()).post(new Runnable() {
public void run() {
AndroidBasicThreadActivity.textView.setText("Hello!! Android Team :-) From child thread.");
}
});
}
}
If using in fragment then simply write
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
// Do something on UiThread
}
});
We use Worker Thread to make Apps smoother and avoid ANR's. We may need to update UI after the heavy process in worker Tread.
The UI can only be updated from UI Thread. In such cases, we use Handler or runOnUiThread both have a Runnable run method that executes in UI Thread.
The onClick method runs in UI thread so don't need to use runOnUiThread here.
Using Kotlin
While in Activity,
this.runOnUiThread {
// Do stuff
}
From Fragment,
activity?.runOnUiThread {
// Do stuff
}
Using Java,
this.runOnUiThread(new Runnable() {
void run() {
// Do stuff
}
});
For fragment use that:
requireActivity().runOnUiThread(() -> {
//your code logic
});
For activity use that:
runOnUiThread(() -> {
//your code logic
});
runOnUiThread is used in a way the UI can be updated with our background thread. For more: https://www.tutorialspoint.com/how-do-we-use-runonuithread-in-android
thy this:
#UiThread
public void logMsg(final String msg) {
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
Log.d("UI thread", "I am the UI thread");
}
});
}
You can use from this sample :
In the following example, we are going to use this facility to publish the result from a
synonym search that was processed by a background thread.
To accomplish the goal during the OnCreate activity callback, we will set up
onClickListener to run searchTask on a created thread.
When the user clicks on the Search button, we will create a Runnable anonymous
class that searches for the word typed in R.id.wordEt EditText and starts the
thread to execute Runnable.
When the search completes, we will create an instance of Runnable SetSynonymResult
to publish the result back on the synonym TextView over the UI thread.
This technique is sometime not the most convenient one, especially when we don't
have access to an Activity instance; therefore, in the following chapters, we are
going to discuss simpler and cleaner techniques to update the UI from a background
computing task.
public class MainActivity extends AppCompatActivity {
class SetSynonymResult implements Runnable {
String synonym;
SetSynonymResult(String synonym) {
this.synonym = synonym;
}
public void run() {
Log.d("AsyncAndroid", String.format("Sending synonym result %s on %d",
synonym, Thread.currentThread().getId()) + " !");
TextView tv = (TextView) findViewById(R.id.synonymTv);
tv.setText(this.synonym);
}
}
;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button search = (Button) findViewById(R.id.searchBut);
final EditText word = (EditText) findViewById(R.id.wordEt);
search.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Runnable searchTask = new Runnable() {
#Override
public void run() {
String result = searchSynomim(word.getText().toString());
Log.d("AsyncAndroid", String.format("Searching for synonym for %s on %s",
word.getText(), Thread.currentThread().getName()));
runOnUiThread(new SetSynonymResult(result));
}
};
Thread thread = new Thread(searchTask);
thread.start();
}
});
}
static int i = 0;
String searchSynomim(String word) {
return ++i % 2 == 0 ? "fake" : "mock";
}
}
Source :
asynchronous android programming Helder Vasconcelos
This is how I use it:
runOnUiThread(new Runnable() {
#Override
public void run() {
//Do something on UiThread
}
});
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gifImageView = (GifImageView) findViewById(R.id.GifImageView);
gifImageView.setGifImageResource(R.drawable.success1);
new Thread(new Runnable() {
#Override
public void run() {
try {
//dummy delay for 2 second
Thread.sleep(8000);
} catch (InterruptedException e) {
e.printStackTrace();
}
//update ui on UI thread
runOnUiThread(new Runnable() {
#Override
public void run() {
gifImageView.setGifImageResource(R.drawable.success);
}
});
}
}).start();
}
Try this: getActivity().runOnUiThread(new Runnable...
It's because:
1) the implicit this in your call to runOnUiThread is referring to AsyncTask, not your fragment.
2) Fragment doesn't have runOnUiThread.
However, Activity does.
Note that Activity just executes the Runnable if you're already on the main thread, otherwise it uses a Handler. You can implement a Handler in your fragment if you don't want to worry about the context of this, it's actually very easy:
// A class instance
private Handler mHandler = new Handler(Looper.getMainLooper());
// anywhere else in your code
mHandler.post(<your runnable>);
// ^ this will always be run on the next run loop on the main thread.