What is the correct way to create an ArrayList array?

Question

Java

Hello, in the program I use an array of object sheets. But when I try to interact with ArrayLists, I get a NullPointerException error. Could someone suggest how to solve this problem?

Answer 1

You create an array of lists of size colors. The array is initially filled with nulls. Therefore, when you take a certain element of this array, and call a method on it, an NPE occurs.