What is a good alternative of LTRIM and RTRIM in Java?

Question

What is a good alternative of JavaScript ltrim() and rtrim() functions in Java?

Answer 1

Using regex may be nice, but it's quite a lot slower than a simple trimming functions:

public static String ltrim(String s) {     int i = 0;     while (i < s.length() && Character.isWhitespace(s.charAt(i))) {         i++;     }     return s.substring(i); }  public static String rtrim(String s) {     int i = s.length()-1;     while (i >= 0 && Character.isWhitespace(s.charAt(i))) {         i--;     }     return s.substring(0,i+1); } 

Source: http://www.fromdev.com/2009/07/playing-with-java-string-trim-basics.html

Also, there are some libraries providing such functions. For example, Spring StringUtils. Apache Commons StringUtils provides similar functions too: strip, stripStart, stripEnd

StringUtils.stripEnd("abc  ", null)    = "abc" 

Answer 2

With a regex you could write:

String s = ... String ltrim = s.replaceAll("^\\s+",""); String rtrim = s.replaceAll("\\s+$",""); 

If you have to do it often, you can create and compile a pattern for better performance:

private final static Pattern LTRIM = Pattern.compile("^\\s+");  public static String ltrim(String s) {     return LTRIM.matcher(s).replaceAll(""); } 

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From a performance perspective, a quick micro benchmark shows (post JIT compilation) that the regex approach is about 5 times slower than the loop (0.49s vs. 0.11s for 1 million ltrim).

I personally find the regex approach more readable and less error prone but if performance is an issue you should use the loop solution.