Why does WindowManager.getdefaultdisplay() warn of a null pointer exception?
Below is some code I have in Android Studio. Android Studio warns that getdefaultdisplay() may throw a null pointer exception.
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
display = windowManager.getDefaultDisplay();
layoutInflater = LayoutInflater.from(context);
actions = new ArrayList<>();
However, when I flip line 3 and 2... it no longer warns. The lines are unrelated though... why is this the case?
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
layoutInflater = LayoutInflater.from(context);
display = windowManager.getDefaultDisplay();
actions = new ArrayList<>();
android 
android-studio asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
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Below is some code I have in Android Studio. Android Studio warns that getdefaultdisplay() may throw a null pointer exception.
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
display = windowManager.getDefaultDisplay();
layoutInflater = LayoutInflater.from(context);
actions = new ArrayList<>();
However, when I flip line 3 and 2... it no longer warns. The lines are unrelated though... why is this the case?
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
layoutInflater = LayoutInflater.from(context);
display = windowManager.getDefaultDisplay();
actions = new ArrayList<>();
asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
829
add a comment |
Below is some code I have in Android Studio. Android Studio warns that getdefaultdisplay() may throw a null pointer exception.
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
display = windowManager.getDefaultDisplay();
layoutInflater = LayoutInflater.from(context);
actions = new ArrayList<>();
However, when I flip line 3 and 2... it no longer warns. The lines are unrelated though... why is this the case?
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
layoutInflater = LayoutInflater.from(context);
display = windowManager.getDefaultDisplay();
actions = new ArrayList<>();
asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
829
Below is some code I have in Android Studio. Android Studio warns that getdefaultdisplay() may throw a null pointer exception.
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
display = windowManager.getDefaultDisplay();
layoutInflater = LayoutInflater.from(context);
actions = new ArrayList<>();
However, when I flip line 3 and 2... it no longer warns. The lines are unrelated though... why is this the case?
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
layoutInflater = LayoutInflater.from(context);
display = windowManager.getDefaultDisplay();
actions = new ArrayList<>();
asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
829
asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
829
asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
829
asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
829
asked Nov 20 '18 at 18:11
EndOfAllEndOfAll
829
829
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Any method that warns NullPointerException are marked as @Nullable, which means that it might return null, so you need to check the result of the getDefaultDisplay() method before using it in order to be sure that the code will not crash because of NullPointerException
Display display = windowManager.getDefaultDisplay()
if(display != null) {
// do what you need here
}
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
Why does Android Studio hide the warning when I add a line between the two?
– EndOfAll
Nov 20 '18 at 18:35
1
becauseLayoutInflater.from(context)will callgetSystemService(...)which is called in getting the windowManager, and this method if did not return null, then android studio will be sure that the first line did not return null because it's the same method.
– Khalid Taha
Nov 20 '18 at 18:42
That's exactly what I was looking for. Thanks Khalid.
– EndOfAll
Nov 20 '18 at 18:43
Welcome, Any Time :)
– Khalid Taha
Nov 20 '18 at 18:44
add a comment |
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1 Answer
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active
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1 Answer
1
active
oldest
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oldest
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active
oldest
votes
Any method that warns NullPointerException are marked as @Nullable, which means that it might return null, so you need to check the result of the getDefaultDisplay() method before using it in order to be sure that the code will not crash because of NullPointerException
Display display = windowManager.getDefaultDisplay()
if(display != null) {
// do what you need here
}
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
Why does Android Studio hide the warning when I add a line between the two?
– EndOfAll
Nov 20 '18 at 18:35
1
becauseLayoutInflater.from(context)will callgetSystemService(...)which is called in getting the windowManager, and this method if did not return null, then android studio will be sure that the first line did not return null because it's the same method.
– Khalid Taha
Nov 20 '18 at 18:42
That's exactly what I was looking for. Thanks Khalid.
– EndOfAll
Nov 20 '18 at 18:43
Welcome, Any Time :)
– Khalid Taha
Nov 20 '18 at 18:44
add a comment |
Any method that warns NullPointerException are marked as @Nullable, which means that it might return null, so you need to check the result of the getDefaultDisplay() method before using it in order to be sure that the code will not crash because of NullPointerException
Display display = windowManager.getDefaultDisplay()
if(display != null) {
// do what you need here
}
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
Why does Android Studio hide the warning when I add a line between the two?
– EndOfAll
Nov 20 '18 at 18:35
1
becauseLayoutInflater.from(context)will callgetSystemService(...)which is called in getting the windowManager, and this method if did not return null, then android studio will be sure that the first line did not return null because it's the same method.
– Khalid Taha
Nov 20 '18 at 18:42
That's exactly what I was looking for. Thanks Khalid.
– EndOfAll
Nov 20 '18 at 18:43
Welcome, Any Time :)
– Khalid Taha
Nov 20 '18 at 18:44
add a comment |
Any method that warns NullPointerException are marked as @Nullable, which means that it might return null, so you need to check the result of the getDefaultDisplay() method before using it in order to be sure that the code will not crash because of NullPointerException
Display display = windowManager.getDefaultDisplay()
if(display != null) {
// do what you need here
}
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
Any method that warns NullPointerException are marked as @Nullable, which means that it might return null, so you need to check the result of the getDefaultDisplay() method before using it in order to be sure that the code will not crash because of NullPointerException
Display display = windowManager.getDefaultDisplay()
if(display != null) {
// do what you need here
}
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
answered Nov 20 '18 at 18:31
Khalid TahaKhalid Taha
1,89211531
1,89211531
Why does Android Studio hide the warning when I add a line between the two?
– EndOfAll
Nov 20 '18 at 18:35
1
becauseLayoutInflater.from(context)will callgetSystemService(...)which is called in getting the windowManager, and this method if did not return null, then android studio will be sure that the first line did not return null because it's the same method.
– Khalid Taha
Nov 20 '18 at 18:42
That's exactly what I was looking for. Thanks Khalid.
– EndOfAll
Nov 20 '18 at 18:43
Welcome, Any Time :)
– Khalid Taha
Nov 20 '18 at 18:44
add a comment |
Why does Android Studio hide the warning when I add a line between the two?
– EndOfAll
Nov 20 '18 at 18:35
1
becauseLayoutInflater.from(context)will callgetSystemService(...)which is called in getting the windowManager, and this method if did not return null, then android studio will be sure that the first line did not return null because it's the same method.
– Khalid Taha
Nov 20 '18 at 18:42
That's exactly what I was looking for. Thanks Khalid.
– EndOfAll
Nov 20 '18 at 18:43
Welcome, Any Time :)
– Khalid Taha
Nov 20 '18 at 18:44
Why does Android Studio hide the warning when I add a line between the two?
– EndOfAll
Nov 20 '18 at 18:35
Why does Android Studio hide the warning when I add a line between the two?
– EndOfAll
Nov 20 '18 at 18:35
1
1
because
LayoutInflater.from(context) will call getSystemService(...) which is called in getting the windowManager, and this method if did not return null, then android studio will be sure that the first line did not return null because it's the same method.– Khalid Taha
Nov 20 '18 at 18:42
because
LayoutInflater.from(context) will call getSystemService(...) which is called in getting the windowManager, and this method if did not return null, then android studio will be sure that the first line did not return null because it's the same method.– Khalid Taha
Nov 20 '18 at 18:42
That's exactly what I was looking for. Thanks Khalid.
– EndOfAll
Nov 20 '18 at 18:43
That's exactly what I was looking for. Thanks Khalid.
– EndOfAll
Nov 20 '18 at 18:43
Welcome, Any Time :)
– Khalid Taha
Nov 20 '18 at 18:44
Welcome, Any Time :)
– Khalid Taha
Nov 20 '18 at 18:44
add a comment |
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