that's that idiom (also that was that)
C1 就这样吧；就这样定了；再没有什么可说的
an expression that shows that something has ended
I won't agree to it and that's that (= I won't discuss it any longer). 我不会同意这件事的，不要再说了。
英汉双解词典收录81607条英汉双解翻译词条，基本涵盖了全部常用单词的读音、翻译及用法，是英语学习的有利工具。