I'm having some problems displaying a ProgressDialog. I have a method that scrapes information from a website, and I want to show the user some kind of "Loading" window instead of the app just looking like it is hanging for a second or two when it is working.
Everything works fine when I don't implement a ProgressDialog & Thread, but as soon as I try to implement a Thread to do the heavy lifting, the AboutMe View window is empty.
I have a MainActivity with a TextView that registers a OnClickListener.
A Click on the TextView does a:
startActivity(new Intent(getBaseContext(), AboutMe.class));
This is most of the AboutMe.class Activity:
public class AboutMe extends Activity {
private ProgressDialog aboutMeProgressDialog;
private String htmlAboutMe = "";
#Override
protected void onCreate(Bundle savedInstanceState) {
getAboutMe(); // Get information from Internet
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFeatureDrawableResource(Window.FEATURE_NO_TITLE, android.R.drawable.ic_dialog_alert);
setContentView(R.layout.abutme);
TextView tvAbout = (TextView) findViewById(R.id.aboutMe);
tvAbout.setText(Html.fromHtml(htmlAboutMe));
}
private void getAboutMe() {
try {
aboutMeProgressDialog = ProgressDialog.show(AboutMe.this, "", "Loading");
new Thread() {
#Override
public void run() {
try {
/** Code to scape webpage **/
}
catch (Exception exp) {
exp.printStackTrace();
}
handler.sendEmptyMessage(0);
}
}.start();
}
catch (Exception ex) {
ex.printStackTrace();
}
}
private final Handler handler = new Handler() {
#Override
public void handleMessage(final Message msg) {
aboutMeProgressDialog.dismiss();
}
};
I'm clearly missing out on something trivial, but I've tried to Google just about everything I can think of, but still can't get a Thread together with ProgressDialog to work for me.
please use run on ui thread method
instead of handler.sendEmptyMessage(0); use this code and remove handle message
runOnUiThread(new Runnable() {
#Override
public void run() {
aboutMeProgressDialog.dismiss();
}
});
dude let me know if this was successful,it works most of times
please call getAboutMe() method after calling super.onCreate(savedInstanceState);
Related
I'm writing an app that will display the current download speed which will be updated every second. My Runnable class is able to update the UI with the value, but when I try to place it inside a loop so that it will continuously run and update the UI TextView every second, the app now hangs.
This is my MainActivity.java:
public class MainActivity extends Activity implements SpeedMeter.TaskRunnableSpeedMeterMethods{
private Thread mSpeedMeterThread;
private Handler mHandler;
private TextView downloadSpeedOutput;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
downloadSpeedOutput = (TextView) findViewById(R.id.speed);
mHandler = new Handler(Looper.getMainLooper()) {
#Override
public void handleMessage(Message inputMessage) {
SpeedMeter speedMeter = (SpeedMeter) inputMessage.obj;
downloadSpeedOutput.setText(Long.toString(speedMeter.getmDownloadSpeedKB()));
}
};
SpeedMeter speedMeter = new SpeedMeter(this);
speedMeter.run();
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(this, MainActivity.class);
}
#Override
public void setSpeedMeterThread(Thread currentThread) {
mSpeedMeterThread = currentThread;
}
#Override
public void setInternetSpeed(SpeedMeter speedMeter) {
Message completeMessage = mHandler.obtainMessage(1, speedMeter);
completeMessage.sendToTarget();
}
}
And here's the other SpeedMeter.java:
public class SpeedMeter implements Runnable {
final TaskRunnableSpeedMeterMethods mMainActivity;
private long mDownloadSpeedKB;
public SpeedMeter(TaskRunnableSpeedMeterMethods mainActivity) {
mMainActivity = mainActivity;
}
#Override
public void run() {
mMainActivity.setSpeedMeterThread(Thread.currentThread());
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_BACKGROUND);
// while(true) {
long rxBytesPrevious = TrafficStats.getTotalRxBytes();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
long rxBytesCurrent = TrafficStats.getTotalRxBytes();
long downloadSpeed = rxBytesCurrent - rxBytesPrevious;
setmDownloadSpeedKB(downloadSpeed/1000);
mMainActivity.setInternetSpeed(this);
// }
}
public long getmDownloadSpeedKB() {
return mDownloadSpeedKB;
}
public void setmDownloadSpeedKB(long mDownloadSpeedKB) {
this.mDownloadSpeedKB = mDownloadSpeedKB;
}
interface TaskRunnableSpeedMeterMethods {
void setSpeedMeterThread(Thread currentThread);
void setInternetSpeed(SpeedMeter speedMeter);
}
}
Any help will be appreciated!
You didnt start your runnable as a new thread instead you called the run function like a normal function (so u do the while loop on ur UI thread which blocks it)
replace
speedMeter.run();<br />
SpeedMeter speedMeter = new SpeedMeter(this);
with
new Thread(new SpeedMeter(this)).start();
see https://docs.oracle.com/javase/tutorial/essential/concurrency/runthread.html for more infos on how to start a Runnable :)
The ideal way to do this would be to create an AsyncTask that would post a message to your UI thread, after it complete the task in the doInBackground() call.
Standards
also the interface structure you are following does not make sense and does not follow good standards. Usually an interface is used as a callback, which is basically what you are doing. But the standard is to say onSomethingChangedA() or onSomethingChangedB() from OnSomethingChangedListener interface.
I think your loop is always true so app hangs its better to create a boolean and use while(mboolean) and put this in your loop
if(something){
mboolean=false;
}
you can also use CountDownTimer.
for example:
new CountDownTimer(miliseconds,1000)
//if you have download speed and download size you can find miliseconds
#Override
public void onTick(long l) {
//something you want to do every seconds
}
#Override
public void onFinish() {
//something you want to do on finish
}
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()
I have a problem, I make a simple application to show you my problem.
I want that setContentView executes and displays the .xml BEFORE the Sleep is executed. I thought everything will be execute in order?
Is there anyone how can say me why it doesn't do that?
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
Thread.sleep(10000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// do something
}
Thanks a lot!
EDIT:
Here is the real OnCreate, seems to be a bigger problem.
Everything with the sleep worked fine, but with the Connect method there are problems.
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ConnectBluetooth();
}
In the ConnectBluetooth() method, I just create a new Socket and try a connection.
With a ned thread or a handler it doesn't seems to work, what should I do then? Use something like an asynctask?
Thanks a lot in common!
The layout isn't displayed until after the creation process has finished, after onResume() is called. However there is no callback for when the layout is displayed, but you can use a Handler and Runnable to do this.
Create a couple field variables:
Handler handler = new Handler();
Runnable delay = new Runnable() {
#Override
public void run() {
// Do something
}
};
And onCreate() call:
handler.postDelayed(delay, 10000);
When you call sleep, you are pausing the UI thread. This will prevent onCreate from returning, which will prevent the framework from completing initialization of your activity, including displaying your view hierarchy.
You should never pause the UI thread like that. If you want to do something after 10 seconds, you can start a separate thread that will do it at the right time:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new Thread() {
#Override
public void run() {
try {
Thread.sleep(10000);
doSomething();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}.start();
}
A cleaner approach would be to use a Handler:
Handler mHandler;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mHandler = new Handler();
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
doSomething();
}
}, 10000);
}
I want to show this dialog, while the thread tries to build up a connection, but the dialog will not show up when I press the button which starts this method.
public void add_mpd(View view) {
dialog = ProgressDialog.show(MainActivity.this, "", "Trying to connect...");
new Thread(new Runnable() {
public void run() {
try {
String child;
EditText new_mpd = (EditText) findViewById(R.id.new_mpd);
child = new_mpd.getText().toString();
mpd = new MPD(child);
children.get(1).add(child);
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (MPDConnectionException e) {
e.printStackTrace();
}
}
}
).start();
adapter.notifyDataSetChanged();
dialog.dismiss();
}
It will not show up because the (blocking) work is done in another thread. That means, the start()-method of the Thread-class will not block.
Ergo, you show the Dialog, the Thread is started and the dialog is immediately dismissed (and therefore closed).
Put the call to dismiss() at the end of your run()-method and it should work just fine.
The above might be working for you, but you should not use the Thread-class directly. There are wrappers around it which are way more comfortable to use.
In Android, if you want to do long-term work off the UI-Thread, you should use an AsyncTask.
Additionaly, to build up on what Lukas said, you can look at this example.
http://www.helloandroid.com/tutorials/using-threads-and-progressdialog
public class ProgressDialogExample extends Activity implements Runnable {
private String pi_string;
private TextView tv;
private ProgressDialog pd;
#Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
tv = (TextView) this.findViewById(R.id.main);
tv.setText("Press any key to start calculation");
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
pd = ProgressDialog.show(this, "Working..", "Calculating Pi", true,
false);
Thread thread = new Thread(this);
thread.start();
return super.onKeyDown(keyCode, event);
}
public void run() {
pi_string = Pi.computePi(800).toString();
handler.sendEmptyMessage(0);
}
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
pd.dismiss();
tv.setText(pi_string);
}
};
}
My application fetches some html code from the internet and when done , displays it on the devices screen. Since it takes about 3-4 seconds to do that , in this time the screen stays black , I'd like to use a progress dialog. This is my code :
package com.nextlogic.golfnews;
// ALL THE IMPORTS ....
public class Activity1 extends Activity {
private ProgressDialog progressDialog;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
progressDialog = ProgressDialog.show(Activity1.this, "", "Loading...");
new Thread()
{
public void run()
{
try
{
sleep(2000);
// HERE I'VE PUT ALL THE FUNCTIONS THAT WORK FOR ME
}
catch (Exception e)
{
Log.e("tag",e.getMessage());
}
// dismiss the progressdialog
progressDialog.dismiss();
}
}.start();
The program works but it doesn't display anything anymore. I have one error in logcat :
Only the original thread that created a view hierarchy can touch its views.
Could you please help me ? Thanks in advance.
The error is explicative enough. To update one visual object you must run the changes inside main thread. A quick and dirty fix could be calling the update code inside runOnUiThread().
However in your case I would use an AsyncTask to download and update the progress of the progress bar. The task has the property to run on UI thread when it ends (so you can update the views there, such as dismissing the progress dialog)
Here is an example how to use an AsyncTask to display a download progress dialog.
Update
Stackoverflow already has the answers to all your question. Here is an example of an AsyncTask to download some content and display the download progress. Just what you want.
Update 2
Ok here is your code using an AsyncTask:
public class Activity1 extends Activity
{
private ProgressDialog progressDialog;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new AsyncTask<Integer, Integer, Boolean>()
{
ProgressDialog progressDialog;
#Override
protected void onPreExecute()
{
/*
* This is executed on UI thread before doInBackground(). It is
* the perfect place to show the progress dialog.
*/
progressDialog = ProgressDialog.show(Activity1.this, "",
"Loading...");
}
#Override
protected Boolean doInBackground(Integer... params)
{
if (params == null)
{
return false;
}
try
{
/*
* This is run on a background thread, so we can sleep here
* or do whatever we want without blocking UI thread. A more
* advanced use would download chunks of fixed size and call
* publishProgress();
*/
Thread.sleep(params[0]);
// HERE I'VE PUT ALL THE FUNCTIONS THAT WORK FOR ME
}
catch (Exception e)
{
Log.e("tag", e.getMessage());
/*
* The task failed
*/
return false;
}
/*
* The task succeeded
*/
return true;
}
#Override
protected void onPostExecute(Boolean result)
{
progressDialog.dismiss();
/*
* Update here your view objects with content from download. It
* is save to dismiss dialogs, update views, etc., since we are
* working on UI thread.
*/
AlertDialog.Builder b = new AlertDialog.Builder(Activity1.this);
b.setTitle(android.R.string.dialog_alert_title);
if (result)
{
b.setMessage("Download succeeded");
}
else
{
b.setMessage("Download failed");
}
b.setPositiveButton(getString(android.R.string.ok),
new DialogInterface.OnClickListener()
{
#Override
public void onClick(DialogInterface dlg, int arg1)
{
dlg.dismiss();
}
});
b.create().show();
}
}.execute(2000);
new Thread()
{
#Override
public void run()
{
// dismiss the progressdialog
progressDialog.dismiss();
}
}.start();
}
}
You need to do this way
runOnUiThread(new Runnable() {
public void run() {
// Do Your Stuff
}});
Dismiss your dialog like this:
Handler handler = new Handler();
handler.post(new Runnable(){
public void run(){
progressDialog.dismiss();
}
});
Create a UI thread after completing network operation
runOnUiThread(new Runnable() {
#Override
public void run() {
progressDialog.dismiss();
}
});
The top answer works great, so here is an example to implement an AsyncTask in MonoDroid (thanks to Greg Shackels): http://mono-for-android.1047100.n5.nabble.com/AsyncTask-td4346647.html