Java regex: X.Y.Z.A

Question

I would like to match all patterns XYZA where X,Y,Z,A are positive integers. For example,

10.4.3.9

11.20.5.6

Right now I have

if (str.matches("\d+\\.\d+\\.\d+\\.\d+")) { ... }

But for some reason this won't compile. Could anyone please enlighten me?

Answer 1

也逃跑之前反斜杠d一次。

if (str.matches("\\d+\\.\\d+\\.\\d+\\.\\d+")) { ... }