Craslitycs send a crash event of null pointer exception
NullPointerException: Attempt to invoke interface method 'java.lang.Object[] java.util.Collection.toArray()' on a null object reference
that refers to mutablelist.addAll(it.list), where it.list is an object from an api response.
When I try to check if this can be null, (it.list != null), AndroidStudio suggest Condition 'it.list != null' is always 'true' so, why this crash? And how can i fix it?
Thanks
You can check your list is empty or not by using kotlin collections function.
Use below function
ArrayList.isNullOrEmpty()
Reference link:
Kotlin collection
Related
Exception has occurred.
_CastError (Null check operator used on a null value)
Null check operator used on a null valueenter image description here
How do I check for user != null using null coalescing operator.
The android documentation shows if user.displayName is null then lastName will be used.
But what if user is null?
How to add null check for user object in the following code ?
android:text="#{user.displayName ?? user.lastName}"
When I run my app and select a dog breed of my choice and like it, I get an error saying -
════════ Exception caught by gesture ═══════════════════════════════════════════
The following NoSuchMethodError was thrown while handling a gesture:
The method 'contains' was called on null.
Receiver: null
Tried calling: contains(Instance of 'BreedsModel')
The likedList list contains all the dog breeds that I have liked. How do I solve this problem?
Here is the link to my code -
My Code
This is because you're calling the contains function on a null variable.
try printing the variable on which you're calling contains function.
print(likedList);
//output will "null"
make sure you're handling the null values
Please refer screenshot in this link, Couldn't find the proper root cause of the null pointer exception.
I'm am a newbie with Android development and using the following example to do something similar: https://stackoverflow.com/a/11626706/5724649
But am getting the following error: "Attempt to invoke virtual method 'java.lang.Object java.util.ArrayList.get(int)' on a null object reference"when I try to set one of the radio button. Also mSource (which is an ArrayList) is null within getView(), so I see why I could get this error, but not sure as to how I should pass the arraylist to getView(). Please help.
The error is about you calling a method on an object which currently "null".
This will also throw the same error:
String a = null;
a.length(); // <<< This will cause an error, because a is null.
You should make sure the following line:
mSource = new ArrayList<RowObject>();
is running before any of these lines:
mSource.get(position).setFirstChecked(true);
mSource.get(position).setFirstChecked(false);
if (mSource.get(position).isFirstChecked()) {