How to split a comma separated String while ignoring escaped commas?

Try:

String array[] = str.split("(?<!\\\\),");

Basically this is saying split on a comma, except where that comma is preceded by two backslashes. This is called a negative lookbehind zero-width assertion.

The regular expression

[^\\],

means "match a character which is not a backslash followed by a comma" - this is why patterns such as t, are matching, because t is a character which is not a backslash.

I think you need to use some sort of negative lookbehind, to capture a , which is not preceded by a \ without capturing the preceding character, something like

(?<!\\),

(BTW, note that I have purposefully not doubly-escaped the backslashes to make this more readable)