The scenario is
I have two threads and a UI thread. The UI thread when clicked on login button creates a ClientThread which creates a socket and runs until the socket is connected, whenever a message is received i use a handler to post message to another thread called ProcessDataThread, now on receiving some messages from server i need to update UI related stuff from ProcessDataThread, I searched around alot and i found these two ways runonUiThread function which i guess can only be run from the Activity Class which is useless and the Asynctask method which i am not sure how to pass the activity context to...
Here is the code
The code executed when clicked on Login Button in the MainActivity
public void onLoginClick(View view)
{
global_constants.clientObject = new ClientThread();
global_constants.clientThread = new Thread(global_constants.clientObject);
global_constants.clientThread.start();
}
The code in ClientThread run method
public class ClientThread implements Runnable {
.......
#Override
public void run() {
......
while(!Thread.currentThread().isInterrupted() && (!CloseThread))
{
byte[] buff;
....
global_constants.updateConversationHandler.post(new ProcessDataThread(buff));
}
}
}
The method code in ProcessDataThread after parsing out the incoming data and stuff
public class ProcessDataThread implements Runnable {
.........
void ProcessLoginFailedPacket(byte[] buff)
{
// how to call the UI thread from here for updating some UI elements??
}
}
[EDIT]
i stored the activity context in a global variable and then did it this way, but i dont know whether it will be safer or not
((Activity)global_constants.MainContext).runOnUiThread(new Runnable(){
public void run()
{
TextView txtErr = (TextView) ((Activity)global_constants.MainContext).findViewById(R.id.errMsg);
txtErr.setVisibility(0);
txtErr.setText(reason);
}
});
You can post a runnable which does the UI operation to main thread as follows,
public class Utils {
public static void runOnUiThread(Runnable runnable){
final Handler UIHandler = new Handler(Looper.getMainLooper());
UIHandler .post(runnable);
}
}
Utils.runOnUiThread(new Runnable() {
#Override
public void run() {
// UI updation related code.
}
});
Related
I need to call a delayed method(runnable) from the NLService thread. However the method never gets called. I would appreciate any help.
public class NLService extends NotificationListenerService {
#Override
public void onNotificationPosted(StatusBarNotification sbn) {
if(sbn.getPackageName().contains("mv.purple.aa")){
AudioManager amanager=(AudioManager)getSystemService(Context.AUDIO_SERVICE);
amanager.setStreamMute(AudioManager.STREAM_NOTIFICATION, true);
//This is the code I am having issues with.
//I used this code to call the method. However it is not working.
private Handler handler = new Handler();
handler.postDelayed(runnable, 100);
}
}
//I want to call the following method
private Runnable runnable = new Runnable() {
#Override
public void run() {
foobar();
}
};
}
The NotificationListenerService is a service which gets activated when notifications are posted within the framework. It does this via a Binder notification internal to the framework, so your onNotificationPosted() callback is being called from one of the binder pool threads, not the usual main thread of your app. In essence, the Handler you are creating is associating itself with a Looper which never gets called because the thread is managed by the internal binder framework rather than the usual main thread or other thread you may create.
Try this: create a HandlerThread the first time your callback is hit (and save it off) and start it. Toss your Runnable over to a Handler you create which is bound to the Looper in the HandlerThread.
There is also a "simpler" solution.
You can create a new Handler inside your onCreate(). Save it as class variable and call it when ever you want again.
Example:
public class NotificationListener extends NotificationListenerService
private mHandler handler;
public void onCreate() {
super.onCreate();
handler = new Handler();
}
#Override
public void onNotificationPosted(StatusBarNotification statusBarNotification) {
handler.postDelayed(new Runnable() {
#Override
public void run() {
// Do something special here :)
}
}, 5*1000);
}
....
// Override other importand methods
....
}
I have a main class;
ClientPlayer extends Activity {
and a service
LotteryServer extends Service implements Runnable {
when trying to use the RunOnUiThread in the run method of this service I am getting compiler error of, "cannot make a static reference to the non static method"
how to fix this?, how I am using the code is shown here;
#Override
public void run() {
// I tried both ClientPlayer.runOnUiThread and LotteryServer.runOnUiThread
// both don't work
ClientPlayer.runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(getApplicationContext(), "from inside thread", Toast.LENGTH_SHORT).show();
}
});
} // end run method
runOnUiThread is not a static method.
If u want to run your runnable on UIThread You can use this
Handler handler = new Handler(Looper.getMainLooper());
This will create a handler for UI Thread.
ClientPlayer extends Activity {
.
.
public static Handler UIHandler;
static
{
UIHandler = new Handler(Looper.getMainLooper());
}
public static void runOnUI(Runnable runnable) {
UIHandler.post(runnable);
}
.
.
.
}
Now u can use this anywhere.
#Override
public void run() {
// I tried both ClientPlayer.runOnUiThread and LotteryServer.runOnUiThread
// both don't work
ClientPlayer.runOnUI(new Runnable() {
public void run() {
Toast.makeText(getApplicationContext(), "from inside thread", Toast.LENGTH_SHORT).show();
}
});
} // end run method
There is a very simple solution to the above problem
just make a static reference of your Activity before your onCreat() method
MainActivity mn;
then initialize it in you onCreat() method like this
mn=MainActivity.this;
and after that you just have to use it to call your runOnUiThread
mn.runOnUiThread(new Runnable() {
public void run() {
tv.setText(fns);///do what
}
});
hope it work.
You can get the instance of your Activity, pass it to the service, and use that instead of the class name.
then you can use:
yourActivity.runOnUiThread( ...
Generally we use this method(RunOnUiThread) when we try to update our UI from a working thread. but As you are Using Service Here, runOnMainThread is seems inappropriate as per your situation.
Better to Use Handler here. Handler is an element associated to the thread where is created, you can post a runnable with your code to the Handler and that runnable will be executed in the thread where the Handler was created.
Create a Handler on your Service in his MainThread and post Runnables on
it / send messages to it.
I have an android application with different activities and they all pull data from a web source. This is done by implementing Runnable and creating a thread with the activity as object. The basic class looks like this:
public ActivityX extends Activity implements Runnable {
#Override
public onResume() {
super.onResume();
Thread someThread = new Thread(this);
someThread.start();
}
#Override
public run() {
try {
// pull web content
}
catch(TimeOutException e) {
// >>> create dialog here <<<
// go back to another activity
}
}
}
I tried to create a dialog helper class with a static method that returns the timeout dialog and then call show() like this:
HelperClass.getTimeOutDialog().show();
but the problem is, I can't call it from inside the run() method, as it's in a different thread. If I try to, I will get a runtime exception stating:
Can't create handler inside thread that has not called Looper.prepare()
I need to do this dialog for nearly a dozen of activities and I really want to get around using a Handler objects and sending a message to call the dialog every time. Isn't there an easier way to do this? I just can't think of any right now unfortunately.
My code would look something like this:
handler.handleEmptyMessage(1);
This is to call the handler. And the following would handle the message:
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
if(msg.what == 1) {
// show dialog here
}
}
};
Cheers
#Override
public run() {
try {
// pull web content
}
catch(TimeOutException e) {
runOnUiThread(new Runnable(){
#Override
public void run() {
// >>> create dialog here <<<
// go back to another activity
}
}
}
}
Try the one above if you don't want to use Handler.
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
if(msg.what == 1) {
// show dialog here
}
}
};
Is this code a part of your activity and not in a thread? If it is a part of your non Ui thread, it would give you the error message. Make sure the handler instance is created in your UI thread because a handler contains an implicit reference to the thread they get created in.
I have this code. I don't know why postDelay make UI frozen in this case. I want the Runnable will run after 100 miliseconds deley and run in 4000 miliseconds.
package com.delaythread;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
public class MyNeedActivity extends Activity implements OnClickListener {
private ProgressBar progressBar;
private final Handler handler = new Handler() {
#Override
public void handleMessage(final Message msg) {
super.handleMessage(msg);
progressBar.setVisibility(ProgressBar.INVISIBLE);
}
};
#Override
public void onClick(final View v) {
if(v.getId() == R.id.button1) {
/* This call doesn't make ProgressBar frozen.
final Thread t = new Thread(new MyRunnable());
t.start();
progressBar.setVisibility(ProgressBar.VISIBLE);
*/
// This makes ProgressBar frozen in 4000 miliseconds.
final boolean b = handler.postDelayed(new MyRunnable(), 100);
if(b) {
progressBar.setVisibility(ProgressBar.VISIBLE);
}
}
}
/** Called when the activity is first created. */
#Override
public void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
((Button)findViewById(R.id.button1)).setOnClickListener(this);
progressBar = (ProgressBar)findViewById(R.id.progressBar1);
}
private class MyRunnable implements Runnable {
#Override
public void run() {
sleep();
}
private void sleep() {
try {
Thread.sleep(4000);
handler.sendEmptyMessage(0);
} catch (final InterruptedException e) {
e.printStackTrace();
}
}
}
}
Update: Actually what I want is AsyncTask executes after a delay time, so I do as this answer Java/android how to start an AsyncTask after 3 seconds of delay?. He said I should use Handler and Runnable.
The following should suit your need according to the post
private final Handler handler = new Handler() {
#Override
public void handleMessage(final Message msg) {
super.handleMessage(msg);
//start Asyntask here. progress show/hide should be done in asynctaswk itself.
}
};
#Override
public void onClick(final View v) {
if(v.getId() == R.id.button1) {
final boolean b = handler.postDelayed(new MyRunnable() , 1000);
}
}
private class MyRunnable implements Runnable {
#Override
public void run() {
handler.sendmessage(0);
}
}
}
You probably want to run your MyRunnable on other thread than main UI one, so you need to start a regular thread for this, like
new Thread(new MyRunnable()).start();
instead of using Handler for this, which queues your runnable to be executed on main UI thread.
BTW, for this purpose Timer with TimerTask would suit better.
The Android Reference for the class Handler points out:
"[...] When you create a new Handler, it is bound to the thread / message queue of the thread that is creating it [...]"
So your Handler, created on instantiation of the Activity, should be running on the UI thread causing it to block when your Runnable is executed.
Try creating a new Thread class in which your Handler is instantiated. Then pass the Runnable to it from your onClick() method. To pass messages back (such as updating the progress bar) you can use another Handler that is running on the UI thread.
You could also save yourself a lot of pain by taking a look at the AsyncTask class.
PS:
Delaying the execution could be done in the AsyncTaskdoInBackground() via a Thread.sleep(100) call. To delay execution on UI thread level you could do the same in AsyncTask.onPreExecute().
As far as I understand it you ask your MyRunnable to run on the GUI thread (of which there is only one); but the only this it does is sleep, effectively causing the GUI thread to freeze waiting for it.
You shouldn't do complicated calcultaions (or, sleep) in the GUI thread.
You may want to read the documentation on threads and the UI thread for a more elaborate description.
Your progress bar isn't updating because you aren't updating it! Try using an AsyncTask, (it runs on a different thread but allows you to update UI elements) and setting the state of the progress bar from within the onProgress method in the Async task.
OR
Just follow this example on the Android Progress Bar page
Try this:
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
//Code to be executed after desired seconds
}
}, seconds*1000);
This would freeze the UI for given number of seconds and the execute the code inside the run()
I have a class which extends the Runnable. This class performs some heavy operation (basically downloads the image from network) in different thread. I want to update the UI (display the downloaded image to an ImageView) from this class. I have tried using handler but did not succeed. Here is my code:
class DataReceiver implements Runnable
{
public Bitmap bmp;
Public Handler uiHandle;
#Override
public void run()
{
while(true)
{
//do image download process here
}
}
}
In main activity
ImageView img = (ImageView)findViewById(R.id.dispImg);
DataReceiver dr=new DataReceiver();
Handler uiHandler = new Handler()
{
#Override
public void handleMessage(Message msg)
{
updateUI();
}
}
dr.uiHandle = uiHandler;
(new Thread(dr)).start();
public void updateUI()
{
img.setBitmap(dr.bmp);
}
Is it the correct method for updating UI?
You could use AsyncTask instead, do what you're currently doing in run() in doInBackground, and then do the UI update in the task's onPostExecute.
almost ;D you need on the class thread add the that linebefore while do:
while(true)
{
//do image download process here
}
uiHandle.sendEmptyMessage(0);
To update the UI from another thread use
activity.runOnUIThread(new Runnable());