How to fix the Null Pointer Exception in Android Studio ?
Whenever Developer is working with the android studio to develop android applications, errors and exceptions are common things that every developer must be ready to deal with. The biggest challenge when it comes to errors and exceptions is not knowing how to handle them or identifying where they are occurring at.
In this tutorial, we shall discuss in detail what is null, what is null pointer exception in android studio, how to handle null pointer exception in android, how to avoid null pointer exception in android, and also how to fix null pointer exception in android.
What is null in Kotlin ?
“Null” is a very familiar keyword among all the programmers out there. It is basically a Literal for Reference datatypes or variables like Arrays, Classes, Interfaces, and Enums. Every primitive data type has a default value set to it (Ex: True and False value for Boolean). Similarly, Reference Datatype Variables have Null value as default if it is not initialized during declaration.
Program Output : — Null
What is a null pointer exception in android ?
A null pointer exception is regarded as a type of error that returns null whenever an object or instance is called. When the result is null, the exception occurs and the thread stops executing and what happens next is that the app crashes.
or
It is a run-time exception that arises when an application or a program tries to access the object reference (accessing methods) which has a null value stored in it. The null value gets stored automatically in the reference variable when we don’t initialize it after declaring as shown below.
FATAL EXCEPTION : -
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.widget.TextView.setText(java.lang.CharSequence)’ on a null object reference
When does null pointer exception occur in android ?
From the definition of a null pointer exception, it is clear that is known as null since the instance referenced is null or the result generated is null.
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Some know ways or reasons why null pointer exception occurs in android according to official android developer’s documentation are;
- When calling a method of a null object
- Sending a null value when a real value is required
- Trying to access or modifying a null value
How to avoid null pointer exception in android ?
From the above listing of what causes null pointer exception in android, you can easily avoid it easily.
First of all, you will need to have a clear understanding of android data types, methods, and objects to ensure that every time you are handling each instance everything is in the correct format.
Also ensure that you are using the correct data types and you have defined and instantiated each data type as they are supposed to, for example, understand how to use global variables and local variables.
In a case where you try to use a local variable outside the defined method or class, you will get the exception.
Ensure that the value you are sending to a method or object is not null and also check the response of a particular action either using logcat or toast to check whether it’s a null result or not.
Handling the Null Pointer Exception in Android Studio ?
To Handle the Null Pointer Exception smoothly without making the app crash, we use the “Try — Catch Block” in Android.
- Try: The Try block executes a piece of code that is likely to crash or a place where the exception occurs.
- Catch: The Catch block will handle the exception that occurred in the Try block smoothly (showing a toast msg on screen) without letting the app crash abruptly.
The coding structure of Try -Catch Block is shown below :-
Program Output :-
We use the try-catch block as shown in the Program code above such that instead of the app crashing, we handle the exception and display it as a toast message.
Conclusion :-
From the above discussion, we have defined what is a null pointer exception, why and when it occurs in android, how to handle and prevent the null pointer exception, and also how to fix the exception.
Given the example we have shown and the image of the error when the exception has occurred, you can now be able to identify it and easily fix it.
That’s it for this tutorial, thank you for following us.
