Stop handler.postDelayed()
Solution 1
You can use:
Handler handler = new Handler()
handler.postDelayed(new Runnable())
Or you can use:
handler.removeCallbacksAndMessages(null);
Docs
public final void removeCallbacksAndMessages (Object token)
Added in API level 1 Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.
Or you could also do like the following:
Handler handler = new Handler()
Runnable myRunnable = new Runnable() {
public void run() {
// do something
}
};
handler.postDelayed(myRunnable,zeit_dauer2);
Then:
handler.removeCallbacks(myRunnable);
Docs
public final void removeCallbacks (Runnable r)
Added in API level 1 Remove any pending posts of Runnable r that are in the message queue.
public final void removeCallbacks (Runnable r, Object token)
Edit:
Change this:
@Override
public void onClick(View v) {
Handler handler = new Handler();
Runnable myRunnable = new Runnable() {
To:
@Override
public void onClick(View v) {
handler = new Handler();
myRunnable = new Runnable() { /* ... */}
Because you have the below. Declared before onCreate
but you re-declared and then initialized it in onClick
leading to a NPE.
Handler handler; // declared before onCreate
Runnable myRunnable;
Solution 2
this may be old, but for those looking for answer you can use this...
public void stopHandler() {
handler.removeMessages(0);
}
cheers
Solution 3
You can define a boolean and change it to false when you want to stop handler. Like this..
boolean stop = false;
handler.postDelayed(new Runnable() {
@Override
public void run() {
//do your work here..
if (!stop) {
handler.postDelayed(this, delay);
}
}
}, delay);
Solution 4
Boolean condition=false; //Instance variable declaration.
//-----------------Inside oncreate---------------------------------------------------
start =(Button)findViewById(R.id.id_start);
start.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
starthandler();
if(condition=true)
{
condition=false;
}
}
});
stop=(Button) findViewById(R.id.id_stoplocatingsmartplug);
stop.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
stophandler();
}
});
}
//-----------------Inside oncreate---------------------------------------------------
public void starthandler()
{
handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
if(!condition)
{
//Do something after 100ms
}
}
}, 5000);
}
public void stophandler()
{
condition=true;
}
Solution 5
Explanation:
Declaring the specific handler before 'onCreate' is necessary. If it is declared inside 'onCreate', they are not sharing the same declaration and thus cannot be identified. This is the problem that the author faced. He has accidentally declared the specific handler inside 'onCreate'.
Solution:
public class MyActivity extends AppCompatActivity implements OnClickListener {
private Button btn;
private Handler handler;
private Runnable myRunnable;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
btn = (Button) findViewById(R.id.trainingsstart);
btn.setOnClickListener(this);
}
@Override
public void onClick(View v) {
handler = new Handler();
myRunnable = new Runnable() {
public void run() {
// Things to be done
}
};
handler.postDelayed(myRunnable, 3000);
}
@Override
public void onBackPressed() {
super.onBackPressed();
handler.removeMessages(0);
}
}
Comments
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basti12354 over 2 years
I call multiple Handlers by new Handler().postDelayed(new Runnable()..... How can I stop it when I click on back?
public class MyActivity extends AppCompatActivity implements OnClickListener { private Button btn; private Handler handler; private Runnable myRunnable; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); btn = (Button) findViewById(R.id.trainingsstart); btn.setOnClickListener(this); } @Override public void onClick(View v) { Handler handler = new Handler(); Runnable myRunnable = new Runnable() { public void run() { // Things to be done } }; handler.postDelayed(myRunnable, 3000); } @Override public void onBackPressed() { super.onBackPressed(); handler.removeCallbacks(myRunnable); } }
I have the problem that my Handlers haven't a name like "myHandler". How can I handle it?
Thanks for help!
Now I got these error:
03-28 17:47:03.662: E/AndroidRuntime(1961): FATAL EXCEPTION: main 03-28 17:47:03.662: E/AndroidRuntime(1961): java.lang.NullPointerException 03-28 17:47:03.662: E/AndroidRuntime(1961): at de.basti12354.tage.uebungen.Tag1.onBackPressed(Tag1.java:120) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.app.Activity.onKeyUp(Activity.java:2159) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.KeyEvent.dispatch(KeyEvent.java:2647) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.app.Activity.dispatchKeyEvent(Activity.java:2389) 03-28 17:47:03.662: E/AndroidRuntime(1961): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1860) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:3791) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3774) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3516) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:3666) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:1982) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1698) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1689) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:1959) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.os.MessageQueue.nativePollOnce(Native Method) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.os.MessageQueue.next(MessageQueue.java:132) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.os.Looper.loop(Looper.java:124) 03-28 17:47:03.662: E/AndroidRuntime(1961): at android.app.ActivityThread.main(ActivityThread.java:5103) 03-28 17:47:03.662: E/AndroidRuntime(1961): at java.lang.reflect.Method.invokeNative(Native Method) 03-28 17:47:03.662: E/AndroidRuntime(1961): at java.lang.reflect.Method.invoke(Method.java:525) 03-28 17:47:03.662: E/AndroidRuntime(1961): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 03-28 17:47:03.662: E/AndroidRuntime(1961): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 03-28 17:47:03.662: E/AndroidRuntime(1961): at dalvik.system.NativeStart.main(Native Method)
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basti12354 about 10 yearsHave add the handler.removeCallbacks(myRunnable); to my onBackPressed() is that right?
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Raghunandan about 10 years@user3433232 use it you want to stop the run
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basti12354 about 10 yearsCan you please look at my code, I try to use your help´, but now I got the errors, you can see at my post.
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Raghunandan about 10 years@user3433232 check the edit. Your Handler was null. You re -declared it in onClick leading to NPE
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Ravi Dhoriya ツ almost 9 yearsThank you so much. It helped me. :)
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misman over 8 yearsI am working on API 16 and handler.removeCallbacks(runnable) doesn't work. But handler.removeCallbacksAndMessages(null); works thanks
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André Kool about 6 yearsPlease explain why this piece of code answers the question.
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vinay shetty about 6 yearsAssume u have 2 Button in XML start and Stop. This code shows the demo of how the handler can be started withe the click of start button and can be stopped by stop button.
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Caio Mar almost 6 yearsIt works but the runnable still runs in the background.
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Dharmishtha over 3 yearsThanks ! In my case following code works perfectly.
handler.removeCallbacksAndMessages(null);
I have put that code in fragment'sonPause()
method and inonDestroy()
method.