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Trim trailing whitespace

/ Published in: Java
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Works almost 9x faster than a regex pattern, and memory usage is better (because Matcher objects aren't created).

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  1. /* instead of 
  2. Pattern p = Pattern.compile("[\\s]+$");
  3. // start timing
  4. p.matcher(str).replaceAll("");
  5.  
  6. The alternative method below averages 400ns, compared to 3500ns of the regex above */
  7.  
  8. 	public static String trimEnd(String str) {
  9. 		int len = str.length();
  10. 		char[] val = str.toCharArray();
  11.  
  12. 		while ((0 < len) && (val[len - 1] <= ' ')) {
  13. 			len--;
  14. 		}
  15.  
  16. 		return (len < str.length()) ? str.substring(0, len) : str;
  17. 	}
  18.  
  19.  
  20. /* Similarly, using a StringCharacterIterator is also faster (although memory usage is worse) - averages 500ns */
  21.  
  22. 	public static String trimEnd(String str) {
  23. 		StringCharacterIterator iter = new StringCharacterIterator(str);
  24.  
  25. 		int len = str.length();
  26. 		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
  27. 				.previous()) {
  28. 			len --;
  29. 		}
  30.  
  31. 		return ((len < str.length())) ? str.substring(0, len)
  32. 				: str;
  33. 	}

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