Java正则表达式仅删除数字之间的空格

Question

I have some strings like:

String a = "Hello 12 2 3 4 45th World!";

I wanna concatenate numbers as: "Hello 12234 45th World"

By trying a.replaceAll("(?<=\\\\d) +(?=\\\\d)", "") , I got the result as: "Hello 1223445th World" .

Is there any way to concatenate only numbers, not number + th ?

Answer 1

(?<=\\d) +(?=\\d+(?:\\s|$))

You can try this.See demo.

https://regex101.com/r/nS2lT4/43

Answer 2

You just need to add a word boundary in the look-ahead to only match numbers as whole words:

a.replaceAll("(?<=\\d) +(?=\\d+\\b)", ""))

Sample code on IDEONE :

String a = "Hello 12 2 3 4 45th World!";
System.out.println(a.replaceAll("(?<=\\d) +(?=\\d+\\b)", ""));

Output:

Hello 12234 45th World!