topic NullpointerException when creating a notebook widget in Data Engineering

NullpointerException when creating a notebook widget

sebasv — Sat, 26 Oct 2024 10:32:12 GMT

To reproduce, execute this line in a notebook (runtime 15.3):

dbutils.widgets.multiselect("foo", None, [None])

Exception raised:

 Py4JJavaError: An error occurred while calling o427.createMultiselectWidget. : java.lang.NullPointerException at com.databricks.backend.daemon.driver.NotebookArguments.trimDefaultValue(NotebookArguments.scala:88)

Re: NullpointerException when creating a notebook widget

esther598 — Sat, 26 Oct 2024 12:00:21 GMT

The error you're encountering is due to trying to use None (or null in Java) as an option in the widget's default values or list of values, which dbutils.widgets.multiselect does not handle properly. The None type in Python is converted to null in Scala/Java (underlying languages in Spark), and this is causing a NullPointerException.

To fix this, you can provide a default value that is a non-null string instead of None. Here’s an example modification:

python
dbutils.widgets.multiselect("foo", "", ["Option1", "Option2"])
Alternatively, if you need the default to be unselected, you can set it to an empty list:

python
dbutils.widgets.multiselect("foo", "", ["Option1", "Option2"])
In this example, replacing None with actual strings will avoid triggering the NullPointerException. Let me know if this resolves the issue or if you need further assistance!

Re: NullpointerException when creating a notebook widget

SathyaSDE — Sat, 26 Oct 2024 13:17:35 GMT

Hi - pls see below

I hope it helps !!