trim() function in Java

1. String .trim()

trim() removes leading and trailing spaces

2. str.replace(" ",""); removes all spaces, including leading and trailing spaces, and the middle

eg: String str = " hell o ";

              String str2 = str.replaceAll(" ","");

                     -- System.out.println(str2);

3, or replaceAll(" +".""); Remove all spaces

4. str = .replaceAll("\s*",""); can replace most whitespace characters, not limited to spaces

s can match any whitespace characters such as spaces, tabs, form feeds, etc. a