Note : I know there are many questions related to this, but still I am not convince, so asking.
I am getting cant create handler inside thread that has not called looper.prepare when I try to show the dialog.
Here is my code...
//this method is called from a different method based on some condition which is inturn called on click a button
private void download() {
thread = new Thread() {
public void run() {
/**** Downloads each tour's Tour.plist file ****/
try {
// do many heavy operations here, like download,
//calling web webvice and starting another activity
This comes at the end
Intent toAudio = new Intent(TourDescription.this,Audio.class);
startActivity(toAudio);
} catch (Exception e) {
}
}
};
thread.start();
}
Now before this actity gets called I am trying to show a dialog. I am trying to place that just before calling Intent.
Can any body please tell me how to do this, as I am not understanding how to solve this
you cannot show a dialog from a child thread.
A dialog can only be showed from within the UI thread/main Thread.
try this from inside the child thread
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO show dialog....
}
});
Related
In the below code, outside is printed before inside. I want the order to be inside first and then outside. So how do I ensure that the Runnable is finished before the second Log is reached?
webView.post(new Runnable() {
#Override
public void run() {
Log.d("check", "inside");
}
});
// some code needed here
Log.d("check", "outside");
Some code must be inserted where to comment is to achieve this.
EDIT: I am doing all the work in a background service.
[P.S.: Those who are curious as to why I am doing this, it is so because unless I add the webview.post, I keep getting the following error: "All WebView methods must be called on the same thread.". Anyway, this shouldn't affect you from answering the question.]
You might try using a CountDownLatch:
final CountDownLatch latch = new CountDownLatch(1);
webView.post(new Runnable() {
#Override
public void run() {
Log.d("check", "inside");
latch.countDown();
}
});
// some code needed here
latch.await();
Log.d("check", "outside");
However, you wouldn't want to use latch.await() on the UI thread, as that's a blocking method. If you wanted to run this on the UI thread it would be best to replace latch.countDown() with a call to a callback method, which would in turn run Log.d("check", "outside").
This question already has an answer here:
Updating UI / runOnUiThread / final variables: How to write lean code that does UI updating when called from another Thread
(1 answer)
Closed 9 years ago.
Good day,
I want to update an image button in my UI from another thread. below is my code that i run in my mains threads onCreate() method.
new Thread(new Runnable() {
public void run() {
ImageButton btn = (ImageButton) findViewById(R.id.connected_icon);
if (netConnection.IsConnected()) {
// Change icon to green
btn.setImageResource(R.drawable.green_small);
} else {
// Change icon to red
btn.setImageResource(R.drawable.red_small);
}
try {
// Sleep for a second before re_checking.
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}).start();
No when i run this i gen an error int he LogCat saying i cannot update the UI from annother thread.
I remember reading soem where once that this is the case so that you don't get multiple threads updating the same UI object at once. But how can i achieve this. i am sure there is a work around?
Thanks
You cannot directly acces UI components from the thread.
The correct way to do this is by creating a handler
final Handler mHandler = new Handler() {
public void handleMessage(Message msg) {
}
};
And send messages to UIThread with
Message msg = new Message();
//TODO: add stuff to message
mHandler.sendMessage(msg);
inside your Thread.
This or use an AsyncTask instead and do the updates from inside of pre, post or progressUpdate methods
UI Elements should be updated only from the UI thread. Use an async task to do background word, and modify the UI in onPostExecute, which runs on the UI thread
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.
In my app i am using soap webservice call , based on the webservice call reply i have to display some messages .,
But after the reply i could not able to do this from the spawned child thread
So how to get back to the main thread and display this after the reply i got
Hope this is clear.. help me how to achieve my requirement
{
Thread t1 = new Thread() {
public void run() {
String threadName = Thread.currentThread().getName();
// There will be delay in this statement while fetching a data from webservice
String returnfromWebservice = webservice(xmlDetails, "generateid");
Log.v("returnfromWebservice",returnfromWebservice);
if( ! returnfromWebservice.equalsIgnoreCase("nil")){
gotid = returnfromWebservice;
gotReply=true;
// dothis();// I could able to do this because this method contains widgets
// I am gettin the error : Only the original thread that created a view hierarchy can touch its views.
//I understand this is because childthread has no controls on widget
/**Suggest me how to get back to main thread*/
}
}};
t1.start();
dothis();// so i am doin here after the completion of it
}
public void dothis{
if(gotReply){
idtext.setText(gotid);
genId.setEnabled(false);
Toast.makeText(WelcomeScorer.this, "Generated ", 500).show();
}
else{
Toast.makeText(WelcomeScorer.this, "Try Once More ", 500).show();
idtext.setText(gotid);
}
}
I am new to android, Is there any best approach in android api to handle this situation ??
You should use the following code to touch your ui elements from another thread
youractivityname.this.runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
}
});
If your thread is in same activity you can use this. Otherwise you should use your activity class object to run the above method.From your code you should call dothis(); after thread has done its job. From your it will call the dothis method immediately after thread has started it wont care whether thread has done its job or not.
The various methods are documented in this article. Using runOnUiThread is probably the simplest.
I am new to android i am trying to create a new thread to invoke another method.
But don't why it is throwing the error.
here is my stub
void test()
{
int i=0;
Toast.makeText(getApplicationContext(), "Testing", Toast.LENGTH_SHORT).show();
}
public void Button2_Click(View v)
{
Thread thread = new Thread()
{
#Override
public void run() {
test();
}
};
thread.start();
}
You can't manipulate the UI from other threads than the main thread, and launching a Toast involves the user interface.
change your test function
void test()
{
int i=0;
Log.d("Test","Testing");
}
now if the thread works you will se a log inside LogCat. If you want to display a Toast from another thread, you must use Handler or runOnUiThread.
Do this is Handler
like this http://www.tutorialforandroid.com/2009/01/using-handler-in-android.html
you can not put Toast inside a Thread. Remove your Toast message from your code. It will work fine.
This is how you can do it.
`new Thread(new Runnable() {
public void run() {
Bitmap b = loadImageFromNetwork();
mImageView.setImageBitmap(b);
}
}).start();
'
Its a bracket mismatch.
If you absolutely must Toast, you should use the runOnUIThread() method and pass it a new Runnable() anonymous class that Toasts in the run() method.
Irrelevantly, this doesn't seem to make a whole lot of sense. Perhaps you want to make test() static. Maybe post a better idea of what you'd like to do and exactly what error you're getting?