Yes, there are 2 different ways you can disable this particular warning:
One way to disable it would be to declare ArrayList as a variable before calling new ArrayList()
var ArrayList = java.util.ArrayList;
var javaArray = new ArrayList();
...
QIE leverages JSHint to perform syntax validation so the other way to disable this warning is using a JSHint Directive.
importPackage(java.util);
/*jshint undef:false*/
var javaArray = new ArrayList();
/*jshint undef:true*/
...
Note that you can disable the warning for just a single line or block of code. Line 2 in the example above disables the "undefined" warning message and line 4 re-enables it. This ensures that other valid "undefined" warnings will be correctly reported in other sections of the code.