.replaceAll(“\\s+$”,“”); 有什么用？

Question

Please anyone tell me what is the difference between:

1. .replaceAll("\\s","");
2. .replaceAll("\\s+","");
3. and .replaceAll("\\s+$","");

Answer 1

s.replaceAll("\\s", "") Replace each space character with nothing.

s.replaceAll("\\s+", "") Replace each group of 1 or more spaces with nothing.

s.replaceAll("\\s+$", "") Replace each group of 1 or more spaces at the end of the string with nothing.

All of these special characters are explained well in the javadoc.