Currently creating an Android app. I have a class called Pollen, on top of my Fragment class, and I am dealing with exception handling within this second class.
Here is my Pollen class.
public static class Pollen
{
#SuppressLint("SimpleDateFormat")
public Pollen(int zipcode, Context context)
{
this.context = context;
this.zipcode = zipcode;
Document doc;
try
{
// pass address to
doc = Jsoup.connect("http://www.wunderground.com/DisplayPollen.asp?Zipcode=" + this.zipcode).get();
// get "location" from XML
Element location = doc.select("div.columns").first();
this.location = location.text();
// get "pollen type" from XML
Element pollenType = doc.select("div.panel h3").first();
this.pollenType = pollenType.text();
SimpleDateFormat format = new SimpleDateFormat("EEE MMMM dd, yyyy");
// add the four items of pollen and dates
// to its respective list
for(int i = 0; i < 4; i++)
{
Element dates = doc.select("td.text-center.even-four").get(i);
Element levels = doc.select("td.levels").get(i);
try
{
pollenMap.put(format.parse(dates.text()), levels.text());
}
catch (ParseException e)
{
Toast toast = Toast.makeText(context, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
return;
}
}
}
catch (IOException e)
{
Toast toast = Toast.makeText(context, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
return;
}
}
}
Since Pollen uses Network tasks, it's under an asynchronous thread which is irrelevant to this question.
Whenever Pollen is met under an exception, despite the Toast, the app would crash.
I was wondering - what is the accepted way to deal with exception on classes outside of the main class?
Your application is crashing because you are creating a toast from outsied the UI thread.
You cannot create a Toast from a class which is not running on the main thread(UI thread). But you can use the runOnUiThread (http://developer.android.com/reference/android/app/Activity.html#runOnUiThread(java.lang.Runnable)) to execute code on the UI thread from your Pollen class.
YourActivity.this.runOnUiThread(new Runnable() {
public void run() {
Toast toast = Toast.makeText(YourActivity.this, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
}
});
For this to work you have to pass the Activity's context to you custom class and use the above method or you can throw exception and catch it from the activity and handle it there.
Related
Following this guide https://developers.google.com/admob/ump/android/quick-start I tried to add everything to my app.
What I did:
link funding choices to admob
added ump to build.gradle
added the app ID to android manifest
set up a dialog for the app in admob and activated it for the app
Then I added this code to my app
ConsentRequestParameters params = new ConsentRequestParameters
.Builder()
.setTagForUnderAgeOfConsent(false)
.build();
consentInformation = UserMessagingPlatform.getConsentInformation(this);
consentInformation.requestConsentInfoUpdate(
this,
params,
new ConsentInformation.OnConsentInfoUpdateSuccessListener() {
#Override
public void onConsentInfoUpdateSuccess() {
// The consent information state was updated.
// You are now ready to check if a form is available.
if (consentInformation.isConsentFormAvailable()) {
loadForm();
}
else {
Context context = getApplicationContext();
CharSequence toastText = "No Form Available";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(context, toastText, duration);
toast.show();
}
}
},
new ConsentInformation.OnConsentInfoUpdateFailureListener() {
#Override
public void onConsentInfoUpdateFailure(FormError formError) {
// Handle the error.
Context context = getApplicationContext();
CharSequence toastText = "Error";
int duration = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(context, toastText, duration);
toast.show();
}
});
and
public void loadForm() {
UserMessagingPlatform.loadConsentForm(
this,
new UserMessagingPlatform.OnConsentFormLoadSuccessListener() {
#Override
public void onConsentFormLoadSuccess(ConsentForm consentForm) {
MainActivity.this.consentForm = consentForm;
if(consentInformation.getConsentStatus() == ConsentInformation.ConsentStatus.REQUIRED) {
consentForm.show(
MainActivity.this,
new ConsentForm.OnConsentFormDismissedListener() {
#Override
public void onConsentFormDismissed(#Nullable FormError formError) {
// Handle dismissal by reloading form.
loadForm();
}
});
}
}
},
new UserMessagingPlatform.OnConsentFormLoadFailureListener() {
#Override
public void onConsentFormLoadFailure(FormError formError) {
// Handle the error
}
}
);
}
However, I always end up getting the toast "Error" landing in onConsentInfoUpdateFailure(FormError formError) independet from testing on my mobile phone or in the virtual device (I am in europe btw).
Am I missing something?
Thanks,
Celdri
I had the same issue and I solved it just by configuring properly my adMob account.
I want to show Toast when no results found after searching ,
I made a simple Toast but toast remains for long time and i want it to disappear after short time
this is code
public boolean onQueryTextSubmit(String query) {
final String[] dose = getResources().getStringArray(R.array.doses);
final String[] use = getResources().getStringArray(R.array.uses);
final String[] composition = getResources().getStringArray(R.array.composition);
final TypedArray img = getResources().obtainTypedArray(R.array.img);
for (String search : suggestions)
{
if (query.equals(search)){
for (int i =0; i<suggestions.length; i++){
if (query.equals(suggestions[i])){
Intent intent = new Intent(MainActivity.this,productDetails.class);
int im = img.getResourceId(i,-1);
intent.putExtra("img",im);
intent.putExtra("dose",dose[i]);
intent.putExtra("use",use[i]);
intent.putExtra("composition",composition[i]);
intent.putExtra("title",suggestions[i].toUpperCase());
startActivity(intent);
}
}
}
else if (query!= search){
Toast.makeText(MainActivity.this, "No Results Found", Toast.LENGTH_SHORT).show();
}
}
return false;
}
Your toast is showing in for loop, he is added to queue multiple time, remove it from loop
Let me start by saying that if image shooting interval is anything more than 1 second it works. For example taking a picture every 2 seconds works perfectly fine. But taking a picture every second sometimes throws java.lang.RuntimeException: takePicture failed. What could be causing this kind of a behaviour?
Here is the code I use and it is in Service:
#Override
public void onCreate()
{
super.onCreate();
prefs = getSharedPreferences("general",Context.MODE_PRIVATE);
handler = new Handler();
shotInterval = prefs.getInt(getString(R.string.prefs_int_imageShootingFrequency),1);
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
Toast.makeText(this, "No camera on this device", Toast.LENGTH_LONG).show();
} else {
cameraId = findBackFacingCamera();
if (cameraId < 0) {
Toast.makeText(this, "No front facing camera found.",Toast.LENGTH_LONG).show();
} else {
camera = Camera.open(cameraId);
}
}
cameraParameters = camera.getParameters();
cameraParameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE); //set camera to continuously auto-focus
camera.setParameters(cameraParameters);
pictureTaker.run(); // Start looping
}
Runnable pictureTaker = new Runnable() {
#Override
public void run() {
try {
takePicture();
} finally {
// 100% guarantee that this always happens, even if
// your update method throws an exception
handler.postDelayed(pictureTaker, shotInterval*1000);
}
}
};
private void takePicture(){
SurfaceView view = new SurfaceView(this);
try {
camera.setPreviewDisplay(view.getHolder());
camera.startPreview();
camera.takePicture(null, null,new PhotoHandler(getApplicationContext()));
} catch (IOException e) {
e.printStackTrace();
}
}
You should launch postDelayed() from the onPictureTaken() callback. You can check the system timer on call to takePicture() and reduce the delay respectively, to keep 1000ms repetition, but maybe once in a while, this delay will reach 0.
I wrote a JSoup HTML scraping class for my Android project. This custom class puts the user-inputted zip code into the constructor, and would parse that HTML. It works in an asynchronous thread from my main thread. Since there is no right way to deal with incorrect zip codes, I had check for null in a particular element, specifically:
if(doc.select("div.columns").first().text() == null)
{
((Activity) context).runOnUiThread(new Runnable() {
public void run()
{
Toast toast = Toast.makeText(context, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
return;
}
});
}
If that particular element is null (meaning that no such data exists for this zip code), it would create a toast to the user. As to why try wouldn't work in this case, it is because JSoup and Java doesn't know whether the parse failed or not, since the web page still loads fine; only, there is no data, which would crash the app from a NullPointerException from the code following it.
Despite my Toast exception handling using .runOnUiThread, my app would still crash. Is there any particular methods that would cancel the operations that follow my null-checking method? I know I am crashing because Toast is not cancelling my operations, and is preceding to execute the following code which causes my NullPointerExceptions.
Posted is my full Pollen constructor.
public Pollen(int zipcode, final Context context)
{
this.context = context;
this.zipcode = zipcode;
Document doc;
try
{
// pass address to Wunderground's website using our inputted zipcode
doc = Jsoup.connect("http://www.wunderground.com/DisplayPollen.asp?Zipcode=" + this.zipcode).get();
if(doc.select("div.columns").first().text() == null)
{
((Activity) context).runOnUiThread(new Runnable() {
public void run()
{
Toast toast = Toast.makeText(context, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
return;
}
});
}
// get "location" from XML
Element location = doc.select("div.columns").first();
this.location = location.text();
// get "pollen type" from XML
Element pollenType = doc.select("div.panel h3").first();
this.pollenType = pollenType.text();
SimpleDateFormat format = new SimpleDateFormat("EEE MMMM dd, yyyy");
// add the four items of pollen and dates
// to its respective list
for(int i = 0; i < 4; i++)
{
Element dates = doc.select("td.text-center.even-four").get(i);
Element levels = doc.select("td.levels").get(i);
try
{
pollenMap.put(format.parse(dates.text()), levels.text());
}
catch (ParseException e)
{
((Activity) context).runOnUiThread(new Runnable() {
public void run()
{
Toast toast = Toast.makeText(context, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
return;
}
});
}
}
}
catch (IOException e)
{
((Activity) context).runOnUiThread(new Runnable() {
public void run()
{
Toast toast = Toast.makeText(context, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
return;
}
});
}
}
tl;dr I still want the Toast to show - but I want on-Toast, to cancel all operations that follow it, since I know that if this particular Toast shows, if the code following it executes, it would crash the app.
Since you already in a try-catch-block, can't you just throw an exception?
public Pollen(int zipcode, final Context context) {
this.context = context;
this.zipcode = zipcode;
Document doc;
try {
// pass address to Wunderground's website using our inputted zipcode
doc = Jsoup.connect("http://www.wunderground.com/DisplayPollen.asp?Zipcode=" + this.zipcode).get();
if(doc.select("div.columns").first().text() == null) {
// Oh no! div.colums is empty. Lets throw an exception, which
// will prevent the code below from executing.
throw new IllegalStateException("div.columns is NULL");
}
// get "location" from XML
Element location = doc.select("div.columns").first();
this.location = location.text();
// get "pollen type" from XML
Element pollenType = doc.select("div.panel h3").first();
this.pollenType = pollenType.text();
SimpleDateFormat format = new SimpleDateFormat("EEE MMMM dd, yyyy");
// add the four items of pollen and dates
// to its respective list
for(int i = 0; i < 4; i++) {
Element dates = doc.select("td.text-center.even-four").get(i);
Element levels = doc.select("td.levels").get(i);
// Removed nested try-catch block
pollenMap.put(format.parse(dates.text()), levels.text());
}
} catch (IOException e) {
displayToast(context);
} catch (ParseException e) {
// We catch the ParseException here instead of nesting try-catch blocks.
displayToast(context);
} catch (IllegalStateException e) {
// Catch the IllegalStateException thrown when div.columns was null,
// and let the user know what went wrong.
displayToast(context);
}
}
private void displayToast(Context context) {
((Activity) context).runOnUiThread(new Runnable() {
public void run() {
Toast toast = Toast.makeText(context, R.string.toast_parse_fail, Toast.LENGTH_LONG);
toast.show();
}
});
}
Similar or the same Question has been answered here
I am creating an Android App, which sends a broadcast message to the network and prepares a list of devices responding back.
Now What I did:
I created an Activity Class DeviceManagerWindow.java which calls a thread Sender.java.
Sender.java is responsible for sending the broadcast message.
Then the DeviceManagerWindow.java calls another thread which is responsible for listening to the devices responding back. The devices responding back will be listed in the Activity as soon as the device responds back. For that I have a TableLayout named deviceList.
What code I have written:
DeviceManagerWindow.java This method is called when a button for search is pressed
public void searchDevice(View v) throws IOException, InterruptedException
{
//Log.v("TableLayout:",view.toString());
sendMulticastFlyport = new Thread(new FlyportSender(MAC));
sendMulticastFlyport.start();
new Thread()
{
public void run()
{
MulticastSocket socketComputer=null;
try
{
socketComputer = new MulticastSocket(WifiConstants.COMPUTER_RECV_PORT);
socketComputer.joinGroup(InetAddress.getByName(WifiConstants.COMPUTER_NETWORK_ADDR));
socketComputer.setSoTimeout(1*60*1000);
byte[] inBufComputer = new byte[1024];
DatagramPacket inPacketComputer = new DatagramPacket(inBufComputer, inBufComputer.length);
while(true)
{
System.out.println("Listening...");
socketComputer.receive(inPacketComputer);
System.out.println("Received");
String msg = new String(inBufComputer, 0, inPacketComputer.getLength());
DeviceInformation device = new DeviceInformation(1, msg, inPacketComputer.getAddress().toString());
addDevice(device, false, 1);
Log.v("Received:","Received Computer From :" + inPacketComputer.getAddress() + " Msg : " + msg);
//System.out.write(inPacket.getData(),0,inPacket.getLength());
System.out.println();
Thread.sleep(2000);
}
}
catch(Exception e)
{
Log.v("Exception:","During Receiving Computer: "+e.toString());
try
{
addDevice(null, true, 1);
}
catch (IOException e1)
{
Log.v("Exception:", "Computer End Error: " +e1);
}
}
finally
{
socketComputer.close();
}
}
}.start();
The following code creates a list:
public void addDevice(DeviceInformation device, boolean bool, int type) throws IOException
{
TableLayout tb = (TableLayout) findViewById(R.id.DeviceList);
Log.v("addDevice","Called");
if(bool)
{
LayoutParams layout = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
TableRow tr = new TableRow(getApplicationContext());
TextView tv = new TextView(getApplicationContext());
System.out.println(tb);
tv.setLayoutParams(layout);
tr.setLayoutParams(layout);
String message;
Log.v("addDevice","Device Timeout");
switch(type)
{
case 1:
computerEnd=true;
break;
case 2:
raspberryEnd=true;
break;
case 3:
flyportEnd=true;
break;
}
if(computerEnd && raspberryEnd && flyportEnd)
{
if(rowCounter>0)
{
message = "No More Devices";
}
else
{
message = "No Devices Found";
}
tv.setText(message);
tv.setTextColor(Color.WHITE);
if(rowCounter%2==0)
{
tr.setBackgroundColor(Color.DKGRAY);
}
else
{
tr.setBackgroundColor(Color.GRAY);
}
tv.setVisibility(1);
tr.addView(tv);
tb.addView(tr);
}
}
else
{
LayoutParams layout = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
TableRow tr = new TableRow(getApplicationContext());
TextView tv = new TextView(getApplicationContext());
tv.setLayoutParams(layout);
tr.setLayoutParams(layout);
Log.v("addDevice","Received");
String textToDisplay = device.getDeviceTypeString()+"\n"+device.getIPAddress(); //Write the text to display
tv.setText(textToDisplay);
tv.setTextColor(Color.WHITE);
Drawable img;
if(device.getDeviceType()==1)
{
img = getApplicationContext().getResources().getDrawable(R.drawable.pc);
}
else if(device.getDeviceType()==2)
{
img = getApplicationContext().getResources().getDrawable(R.drawable.raspberry);
}
else
{
img = getApplicationContext().getResources().getDrawable(R.drawable.flyport);
}
img.setBounds(0,0,70,45);
tv.setCompoundDrawables(null, null, img, null);
tv.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
}
});
if(rowCounter%2==0)
{
tr.setBackgroundColor(Color.DKGRAY);
}
else
{
tr.setBackgroundColor(Color.GRAY);
}
rowCounter++;
Log.v("Result","Device Added");
}
}
Now it is showing me an error in the logCat as:
05-11 22:01:10.165: E/AndroidRuntime(13873): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
What I have figured out from this is only the UIThread is allowed to access the Views that is created.
Previously I had tried:
new Thread()
{
public void run()
{
runOnUiThread(){
MulticastSocket socketComputer=null;
try
{
....
....
....
}
}
And that time I received an error:
Main thread cannot access Network
Before that I had tried to use synchronized methods which was called from the Receiving.java Thread File. but It also gave an error of not creating the list.
I have tried all possible ways.
Now what whould I do.?
You figured it out right. Now you can learn to either use a Handler to pass information to the UI thread (see http://www.techotopia.com/index.php/A_Basic_Overview_of_Android_Threads_and_Thread_handlers) or AsyncTask (see http://developer.android.com/reference/android/os/AsyncTask.html).
I personally prefer AsyncTask. You can paste the code which performs the search into the doInBackground() method (not need to use a separate thread, doInBackground() already does that for you) and paste the UI-related code (the list creation code) into the onPostExecute() method. Search for further examples of AsyncTask if it is not sufficiently clear how it works from the link.
EDIT: If you intend your device search code to run indefinitely, then you have to resort to Handler, as AsyncTask expects the doInBackground() method to finish before running onPostExecute(). See which option better suits your needs.