Stop handler postDelayed

Question

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

this may be old  but for those looking for answer you can use this     public void stopHandler        handler removeMessages 0       cheers

[android] Stop handler.postDelayed()

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