Fixed some memory leaks in the sample app

Author: wdullaer

sample/src/main/java/com/wdullaer/datetimepickerexample/DatePickerFragment.java

@@ -128,13 +128,22 @@ public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                     dpd.setScrollOrientation(DatePickerDialog.ScrollOrientation.VERTICAL);
                 }
             }
-            dpd.setOnCancelListener(dialog -> Log.d("DatePickerDialog", "Dialog was cancelled"));
+            dpd.setOnCancelListener(dialog -> {
+                Log.d("DatePickerDialog", "Dialog was cancelled");
+                dpd = null;
+            });
             dpd.show(requireFragmentManager(), "Datepickerdialog");
         });
 
         return view;
     }
 
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        dpd = null;
+    }
+
     @Override
     public void onResume() {
         super.onResume();
@@ -146,5 +155,6 @@ public void onResume() {
     public void onDateSet(DatePickerDialog view, int year, int monthOfYear, int dayOfMonth) {
         String date = "You picked the following date: "+dayOfMonth+"/"+(++monthOfYear)+"/"+year;
         dateTextView.setText(date);
+        dpd = null;
     }
 }

sample/src/main/java/com/wdullaer/datetimepickerexample/TimePickerFragment.java

@@ -120,13 +120,22 @@ public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                 };
                 tpd.setDisabledTimes(disabledTimes);
             }
-            tpd.setOnCancelListener(dialogInterface -> Log.d("TimePicker", "Dialog was cancelled"));
+            tpd.setOnCancelListener(dialogInterface -> {
+                Log.d("TimePicker", "Dialog was cancelled");
+                tpd = null;
+            });
             tpd.show(requireFragmentManager(), "Timepickerdialog");
         });
 
         return view;
     }
 
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        tpd = null;
+    }
+
     @Override
     public void onResume() {
         super.onResume();
@@ -141,5 +150,6 @@ public void onTimeSet(TimePickerDialog view, int hourOfDay, int minute, int seco
         String secondString = second < 10 ? "0"+second : ""+second;
         String time = "You picked the following time: "+hourString+"h"+minuteString+"m"+secondString+"s";
         timeTextView.setText(time);
+        tpd = null;
     }
 }