Personal opinion:
If you want to write a basic data type for List's generic type, you generally need to use its wrapper class: List
In Java, arrays are treated as objects (reference types). Therefore, when you new an int[], such as arr1, then arr1 is an object (reference type), so it can be written in angle brackets.
Then you can write a for loop (or for-each loop) and use the get() method to get the elements in the List. You can find that each time you take out an array of int or char .
The Arrays.asList() method returns a List
How to add non-basic type arrays to references in List:
List
list3.add(arr3);