Cannot resolve method 'split()'

This error occurs when you try to use the `split()` method on a data type that does not have the method defined.

For example, you might try to split an integer or a boolean value using the `split()` method, which is not valid because these data types do not have the method defined.

To fix this error, you need to make sure that you are using the `split()` method on a string data type. You can do this by converting the data type to a string using the `toString()` method or by making sure that the variable you are using is a string data type.

Here is an example of how to split a string:

String str = "Hello, World!";
String[] words = str.split(",");

In this example, the `split()` method is used on the `str` variable, which is a string data type. The method splits the string at the comma, and the resulting array contains the two words "Hello" and " World!".