What error may occur in improperly written XML code for a TextView?

When writing XML code for a TextView, it is essential that strings used in the text attributes are quoted correctly. In XML, attributes such as android:text require that the values assigned to them be wrapped in either single or double quotes. If these strings are not correctly quoted, the XML parser will not recognize them, leading to a compilation error when building the application. This ensures that the attribute values are interpreted properly.

Improperly quoting string values can result in an invalid XML structure, making it impossible for the Android framework to render the TextView as intended. Therefore, ensuring that strings are correctly enclosed in quotes is crucial for the proper functioning of the UI element.