Cannot convert named undefined to int type.

Undefined is a special value, which is usually used to indicate that a variable has no assignment. References to undefined values return the special value undefined.

It depends on how you submit it in ajax. Js variable is passed to the back, undefined or undefined return. Of course, the conversion is wrong.

The key depends on

When two parameters, curpage and size, are there values or undefined?

You'd better check whether the variables in the jsp page form have been assigned.