Why does null pointer exception occur?

Why does null pointer exception occur?

What Causes NullPointerException. The NullPointerException occurs due to a situation in application code where an uninitialized object is attempted to be accessed or modified. Essentially, this means the object reference does not point anywhere and has a null value.

How does Javatpoint handle null pointer exception?

To avoid Null pointer exceptions, we need to ensure that all objects are initialized with a legitimate value before using them. We must verify at the time of defining a reference variable that it is not null since performing any operations on a null reference variable leads to the null pointer exception.

Why NullPointerException is bad?

A NPE is considered the result of a programming error. A strictly correct program should never generate one. The reason seeing it caught is bad is it usually means that the code threw one, and the programmer decided to just catch it and cover it up, rather than fix the broken code that caused it in the first place!

What does contentresolver.query ( client ) do?

The ContentResolver.query() client method always returns a Cursor containing the columns specified by the query’s projection for the rows that match the query’s selection criteria. A Cursor object provides random read access to the rows and columns it contains.

When to return NULL in getcontext ( ) method?

Retrieves the Context this provider is running in. Only available once onCreate () has been called — this will return null in the constructor. So the getContext () method does not return null in insert (), update () or delete (), because onCreate () will be called before these calls.

How does getcontentresolver ( ) work in Android?

The ContentResolver object communicates with the provider object, an instance of a class that implements ContentProvider. The provider object receives data requests from clients, performs the requested action, and returns the results.

What happens if mcontext of contentprovider is null?

Your solution is just the same, which means if mContext of ContentProvider is null, your reference will also be null. So there is no need for this. To help you out, this is just a warning of your IDE if make such a construct yourself. But in this case there will always be context, because the ContentProvider is generated by your system.

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