Why i can't force Android ANR with this code?
No log messages or pop up. The application is just launched lazily.
[UPDATE]
I can't get it even sleeping a View.setOnClickListener or BroadcastReceiver.onReceive!
Is there a trick?
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) {
Log.e("Test", "", e);
}
}
}
I'm using Samsung GT-6200L with stock Android 3.2
Try it in onTouchEvent. In onCreate your activity is not fully running
#Override
public boolean onTouchEvent(MotionEvent event) {
Log.d(TAG,"onTouchEvent");
while(true) {}
}
The ANR-WatchDog project has a test app that produces ANRs in a reliable manner (as reliable as ANRs can be): the app hangs because of a deadlock.
The gist of it:
Prepare a lock object as a private field in your activity:
final Object mutex = new Object();
Have a thread that performs some work in a critical section, and an android.os.Handler that posts work depending on the same lock.
new Thread(new Runnable() {
#Override
public void run() {
synchronized (mutex) {
while (true) {
try {
Thread.sleep(60000);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}).start();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
synchronized (mutex) {
// Shouldn't happen
throw new IllegalStateException();
}
}
}, 1000);
Putting the above code snippet inside a button click handler, for example, should do the trick.
I've been facing the same issue yesterday, and I've found out that using a plain debug build ANR dialogs simply won't show up. (Although the UI thread was completely hanged.)
But after exporting and properly signing the application the dialogs were popped up properly (in every cases mentioned above). However I am still not sure what really prevents to pop up ANR messages, maybe someone else can clarify this later...
Try using:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int a=0;
while(true) {
a++;
}
}
Your code probably didn't work because it got setup too early, and the Activity probably wasn't fully initialized and created yet. With the above code, launch the activity and touch/swipe on the screen and wait for the ANR dialog to popup.
Make a button in your activity.
public void onBtn1(View v) {
int a = 0;
while(true) {
a++;
}
}
Make the button execute the above code.
Spam click the button with your finger =)
I used this code for force ANR
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void force(View view){
while(true) {}
}
I just created a simple button in the xml file and set android:onClick=force
Related
I'm trying to check existence of 2000 files in Asynctask.
In the initial execution, it works well.
But if I restart app about 10 times , loading speed slows down.
As I am a beginner developer, I lack understanding of Asynctask.
Please give me some advices.
This is my splash activity
public class SplashActivity extends AppCompatActivity {
getFirstData gfd;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splash);
gfd = new getFirstData(this, (TextView) findViewById(R.id.textView18));
gfd.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, this);
}
#Override
protected void onDestroy() {
try
{
if (gfd.getStatus() == AsyncTask.Status.RUNNING)
{
gfd.cancel(true);
}
else
{
}
}
catch (Exception e)
{
}
super.onDestroy();
}
}
And this is my asynctask code
public class getFirstData extends AsyncTask<Context,Integer,Void> {
private PowerManager.WakeLock mWakeLock;
private Context context;
private TextView textview;
getFirstData(Context context,TextView tv){
this.context=context;
this.textview=tv;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
PowerManager pm = (PowerManager) this.context.getSystemService(Context.POWER_SERVICE);
mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, getClass().getName());
mWakeLock.acquire();
}
#Override
protected Void doInBackground(Context...contexts) {
Database.addDB();
for (int i = 0; i < Database.db_list.size(); i++) {
File filetemp = Database.getFilename(i, ".pdf", Database.db_list);
if (filetemp.exists()) {
Database.db_list.get(i).isDownloaded = true;
}
publishProgress(Database.db_list.size(),i);
}
return null;
}
#Override
protected void onProgressUpdate(Integer... params) {
super.onProgressUpdate(params);
textview.setText("Load("+params[1]*100/params[0]+"%)");
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
Intent intent = new Intent(this.context, MainActivity.class);
this.context.startActivity(intent);
((Activity)this.context).finish();
}
}
AsyncTask cancel method doesn't immediately stop your AsyncTask, instead it'll only 'cancel' after doInBackground completes. (Reference)
Calling this method will result in onCancelled(java.lang.Object) being invoked on the UI thread after doInBackground(java.lang.Object[]) returns. Calling this method guarantees that onPostExecute(Object) is never subsequently invoked, even if cancel returns false, but onPostExecute(Result) has not yet run. To finish the task as early as possible, check isCancelled() periodically from doInBackground(java.lang.Object[]).
If you want your AsyncTask to end as quickly as possible, just make a check every 10 (or whatever value you deem suitable) iterations. Something along the following lines should work.
#Override
protected Void doInBackground(Context...contexts) {
Database.addDB();
for (int i = 0; i < Database.db_list.size(); i++) {
File filetemp = Database.getFilename(i, ".pdf", Database.db_list);
if (filetemp.exists()) {
Database.db_list.get(i).isDownloaded = true;
}
publishProgress(Database.db_list.size(),i);
if (i%10==0 && isCancelled()) {
break;
}
}
return null;
}
I see you actually read the manual! Good work!
While its a good effort, unfortunately, the basic approach really just won't work.
I'm not completely clear on what is making the app slow down. If by "restart" you mean back-arrow and then start from the Desktop, then in is probably because you have many downloads running at once. Note that there is no way to stop your AsyncTask once you start it: cancel doesn't actually do anything, unless you implement it.
Your AsyncTask has all the typical problems with leaking a context (Studio is probably yelling at you about this already: pay attention). There is no reason to believe that the Activity that starts the task is still there when the task completes.
My suggestion is that you separate the state of the app from the Activity that views that state. This approach has lots of names but usually something like ViewModel. The View model is some kind of singleton that only allows users to see the Splash page until its state changes (it has the files downloaded). Then it shows the MainActivity.
Good luck!
I'm trying to make a simple little program that will increment a number once a second. In this case, I'm implementing a thread that should loop once per second and add 1 to "potato" each time it loops. This works fine until it gets back to the display method potatoDisp(). For some reason this causes my app to crash. Removing potatoDisp() from run() fixes the problem, but the display is not updated as "potato" increases.
public int potato = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
potatoDisp();
start();
}
public void potatoDisp() {
TextView text = (TextView) findViewById(R.id.textView1);
text.setText("You currently have " + potato + " potatoes");
}
public void start() {
Thread thread = new Thread(this);
thread.start();
}
#Override
public void run() {
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
return;
}
potato++;
potatoDisp();
}
}
I'm doing this for an Android app, if that helps. I've tried searching for an answer but I'm pretty lost when it comes to the proper way to work threads.
You need a runnable / handler like this:
private Runnable potatoRun = new Runnable() {
#Override
public void run () {
potatoDisp();
}
};
then change
potatoDisp();
to:
runOnUiThread(potatoRun);
You can't update the views when you're not on the UI thread.
You are probably getting an exception for updating the UI in the background. Since, potatoDisp(); is called from a background Thread but that function updates the UI it will give you problems. You need to call it with runOnUiThread().
#Override
public void run() {
while (true) {
try
{
Thread.sleep(1000);
} catch (InterruptedException e) {
return;
}
potato++;
runOnUiThread(new Runnable()
{
#Override
public void run()
{
potatoDisp();
}
});
}
}
Something like this should work.
The issue is that you are trying to update the UI (calling text.setText(...)) on a thread other than the main UI thread.
While I would suggest using a TimerTask instead of calling Thread.sleep(...), there are two main ways to edit your current code to work as expected.
-- Use a Handler
Define a Handler class that will accept messages and update your UI as needed. For example:
private final String POTATO_COUNT = "num_potatoes";
Handler handler = new Handler() {
public void handleMessage(Message msg) {
int numPotatoes = msg.getData.getInt(POTATO_COUNT);
mText.setText("You currently have " + numPotatoes + " potatoes");
}
}
Then in your code where you want to call your handler to update your text view, whether or not you are on the main UI thread, do the following:
Bundle bundle = new Bundle();
bundle.putInt(POTATO_COUNT, potato);
Message msg = new Message();
msg.setData(bundle);
handler.sendMessage(msg);
-- Call runOnUiThread(...)
#Override
public void run() {
while (true) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
return;
}
potato++;
runOnUiThread(new Runnable()
{
public void run()
{
potatoDisp();
}
}
}
}
I think you should be using Async Task to update the UI from a thread: http://developer.android.com/reference/android/os/AsyncTask.html
I would like to display an image at the opening of my application Android (Java), is like a toast in full screen only.
That is, when you open the application and an image appears and disappears after you start the program.
What better way to do this?
You mean Splash screen? If so, here is your answer: Splash Screen
It's called a SplashScreen
the links are here
http://www.anddev.org/simple_splash_screen-t811.html
and here
http://blog.iangclifton.com/2011/01/01/android-splash-screens-done-right/
Cheers
I think you are looking for Splash screen in android.
I found above link really helpful. There are lots of other article available. Just ask Google
You have to create an Activity with this image on the layout.
Then within this activity, create a Thread that will sleep for X seconds. When the Thread slept enough, start a new activity.
This is an example code :
public class SplashActivity extends Activity {
public StartThread th;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splash);
th = new StartThread(this);
th.start();
}
}
class StartThread extends Thread {
SplashActivity parentActivity;
public StartThread(SplashActivity splashActivity) {
this.parentActivity = splashActivity;
}
#Override
public void run() {
super.run();
try {
this.sleep(3000);
}
catch (InterruptedException e) {
e.printStackTrace();
}
finally {
Intent menu = new Intent("com.yourpackage.yourapplication.NEXTACTIVITY");
this.parentActivity.startActivity(menu);
this.parentActivity.finish();
this.parentActivity.th = null;
}
}
}
Can someone explain to me 2 things about the thread code that I finally made almost working the way it should. I want to do a periodic task in the background every x seconds and be able to stop and start it at will. I coded that based on the examples I found, but I'm not sure if I made it in the right way. For the purpose of debugging, the task is displaying a time with custom showTime().
public class LoopExampleActivity extends Activity {
TextView Napis, Napis2;
Button button1,button_start,button_stop;
Handler handler = new Handler();
Boolean tread1_running = true;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Napis = (TextView) findViewById(R.id.textView1);
Napis2 = (TextView) findViewById(R.id.textView2);
button1 = (Button) findViewById(R.id.button1);
button_stop = (Button) findViewById(R.id.button_stop);
button_start = (Button) findViewById(R.id.button_start);
button_stop.setOnClickListener(new OnClickListener() {
#Override
public void onClick (View v) {
tread1_running = false;
}
});
button_start.setOnClickListener(new OnClickListener() {
#Override
public void onClick (View v) {
tread1_running = true;
}
});
thread.start();
}// endof onCreate
final Runnable r = new Runnable()
{
public void run()
{
handler.postDelayed(this, 1000);
showTime(Napis2);
}
};
Thread thread = new Thread()
{
#Override
public void run() {
try {
while(tread1_running) {
sleep(1000);
handler.post(r);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
}
Now the questions are:
1)Will my thread quit forever if I stop it with the stop button?
2)Why can't I start it again with the start_button? If I add the tread.start() in a button, will it crash?
3) I tried a second version when I let the thread run and put a condition into the handler. The only way I can get it to work is to loop conditionaly in the handler by adding an
if (thread1_running) {
handler.postDelayed(this, 2000);
showTime(Napis2);
}
And changing the condition in a thread start to while (true) but then I have an open thread that is running all the time and I start and stop it in a handler, and it posts more and more handlers.
So, finally I get to the point it looks like that:
final Runnable r = new Runnable()
{
public void run()
{
if (thread1_running) handler.postDelayed(this, 1000);
showTime(Napis2);
}
};
Thread thread = new Thread()
{
#Override
public void run() {
try {
while(true) {
sleep(1000);
if (thread1_running) handler.post(r);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
Is the proper way to do that is to start and stop a whole thread? Or that is the best way?
The best way to achieve something like that would be, in my humble opinion, to postDelayed(Runnable, long).
You could do something like this. Class definition:
private Handler mMessageHandler = new Handler();
private Runnable mUpdaterRunnable = new Runnable() {
public void run() {
doStuff();
showTime(Napis2);
mMessageHandler.postDelayed(mUpdaterRunnable, 1000);
}
};
And control true run/stop like this:
To start:
mMessageHandler.postDelayed(mUpdaterRunnable, 1000);
And to stop:
mMessageHandler.removeCallbacks(mUpdaterRunnable);
It's much much simpler, in my humble opinion.
Threads a described by a state machine in java.
When a thread get outs of its run method, it enters in the stopped state and can't be restarted.
You should always stop a thread by getting it out of its run method as you do, it s the proper way to do it.
If you want to "restart the thread", start a new instance of your thread class.
You should better encapsulate your thread and its running field. It should be inside your thread class and the class should offer a public method to swich the boolean. No one cares about your datastructure, hide them. :)
You should consider using runOnUIThread for your runnable, its much easier to use than handlers.
I have a class with a thread and a progress dialog. When the thread stops, the dialog must dismiss. But if the thread stops, the app crashes :S Has anyone an idea whats wrong?
public class Main extends Activity {
public static ProgressDialog LoadingDialog = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LoadingDialog.show(AndroidRSSReader.this, "Laden...", "Even geduld aub...", true);
setContentView(R.layout.main);
startUp();
new Thread(new Runnable(){
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
LoadingDialog.dismiss();
}
}).start();
}
LoadingDialog is still null when you call dismiss. You need to make sure and assign it to something (like your progress bar).
LoadingDialog = ProgressDialog.show(AndroidRSSReader.this, "Laden...", "Even geduld aub...", true);
Seems you have problems in dismissing a dialog try using a Handler to perform an action on UI thread :
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
// perform logic
if(LoadingDialog!=null)//first check if dialog is not null.This might be a reason for crashing
LoadingDialog.dismiss();
LoadingDialog=null
}
};
& then call it in your activity by simply calling handler.sendEmptyMessage(0);
&you are done.
Additional advice :also have a look at AsyncTask to perform async operation.