Trim trailing whitespace - Java Snipplr Social Repository

Revision: 14067

at May 18, 2009 10:08 by monkey103

Updated Code

/* instead of 
Pattern p = Pattern.compile("[\\s]+$");
// start timing
p.matcher(str).replaceAll("");

The alternative method below averages 400ns, compared to 3500ns of the regex above */

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}


/* Similarly, using a StringCharacterIterator is also faster (although memory usage is worse) - averages 500ns */

	public static String trimEnd(String str) {
		StringCharacterIterator iter = new StringCharacterIterator(str);

		int len = str.length();
		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
				.previous()) {
			len --;
		}

		return ((len < str.length())) ? str.substring(0, len)
				: str;
	}

Revision: 14066

at May 18, 2009 10:07 by monkey103

Updated Code

/* instead of 
Pattern p = Pattern.compile("[\\s]+$");
// start timing
p.matcher(str).replaceAll("");

The alternative method below averages 400ns, compared to the regex above*/

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}


/* Similarly, using a StringCharacterIterator is also faster (although memory usage is worse) - averages 500ns */

	public static String trimEnd(String str) {
		StringCharacterIterator iter = new StringCharacterIterator(str);

		int len = str.length();
		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
				.previous()) {
			len --;
		}

		return ((len < str.length())) ? str.substring(0, len)
				: str;
	}

Revision: 14065

at May 18, 2009 10:06 by monkey103

Updated Code

/* instead of 
Pattern p = Pattern.compile("[\\s]+$");
// start timing
p.matcher(str).replaceAll("");

This alternative method averages 400ns */

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}


/* Similarly, using a StringCharacterIterator is also faster (although memory usage is worse) - averages 500ns */

	public static String trimEnd(String str) {
		StringCharacterIterator iter = new StringCharacterIterator(str);

		int len = str.length();
		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
				.previous()) {
			len --;
		}

		return ((len < str.length())) ? str.substring(0, len)
				: str;
	}

Revision: 14064

at May 18, 2009 09:52 by monkey103

Updated Code

/* instead of Pattern p = Pattern.compile("[\\s]+$").matcher(str).replaceAll("") - averages 400ns */

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}


/* Similarly, using a StringCharacterIterator is also faster (although memory usage is worse) - averages 500ns */

	public static String trimEnd(String str) {
		StringCharacterIterator iter = new StringCharacterIterator(str);

		int len = str.length();
		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
				.previous()) {
			len --;
		}

		return ((len < str.length())) ? str.substring(0, len)
				: str;
	}

Revision: 14063

at May 18, 2009 09:51 by monkey103

Updated Code

/* instead of Pattern p = Pattern.compile("[\\s]+$").matcher(str).replaceAll("") - averages 300ns */

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}


/* Similarly, using a StringCharacterIterator is also ~6x faster (although memory usage is worse) - avgs 400ns */

	public static String trimEnd(String str) {
		StringCharacterIterator iter = new StringCharacterIterator(str);

		int len = str.length();
		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
				.previous()) {
			len --;
		}

		return ((len < str.length())) ? str.substring(0, len)
				: str;
	}

Revision: 14062

at May 18, 2009 09:48 by monkey103

Updated Code

/* instead of Pattern p = Pattern.compile("[\\s]+$").matcher(str).replaceAll("") */

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}


/* Similarly, using a StringCharacterIterator is also ~6x faster (although memory usage is worse) */

	public static String trimEnd(String str) {
		StringCharacterIterator iter = new StringCharacterIterator(str);

		int len = str.length();
		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
				.previous()) {
			len --;
		}

		return ((len < str.length())) ? str.substring(0, len)
				: str;
	}

Revision: 14061

at May 18, 2009 09:48 by monkey103

Updated Code

/* instead of Pattern p = Pattern.compile("[\\s]+$").matcher(str).replaceAll("") */

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}


/* Similarly, using a StringCharacterIterator is also ~6x faster (although memory usage is worse */

	public static String trimEnd(String str) {
		StringCharacterIterator iter = new StringCharacterIterator(str);

		int len = str.length();
		for (char c = iter.last(); c != CharacterIterator.DONE && c <= ' '; c = iter
				.previous()) {
			len --;
		}

		return ((len < str.length())) ? str.substring(0, len)
				: str;
	}

Revision: 14060

at May 18, 2009 09:46 by monkey103

Updated Code

// instead of Pattern p = Pattern.compile("[\\s]+$").matcher(str).replaceAll("")

	public static String trimEnd(String str) {
		int len = str.length();
		char[] val = str.toCharArray();

		while ((0 < len) && (val[len - 1] <= ' ')) {
			len--;
		}
			
		return (len < str.length()) ? str.substring(0, len) : str;
	}

Revision: 14059

at May 18, 2009 09:44 by monkey103

Updated Code

// instead of Pattern p = Pattern.compile("[\\s]+$").matcher(str).replaceAll("")

public static String trimEnd(String str) {
	int len = str.length();
	int st = 0;
	char[] val = str.toCharArray();

	while ((st < len) && (val[st  + len - 1] <= ' ')) {
		len--;
	}
		
	return ((st > 0) || (len < str.length())) ? str.substring(st, len) : str;
}

Revision: 14058

at May 18, 2009 09:38 by monkey103

Initial Code

// instead of Pattern p = Pattern.compile("[\\s]+$").matcher(str).replaceAll("")

public static String trimEnd(String str) {
		int len = str.length();
		int st = 0;
		int off = 0; /* avoid getfield opcode */
		char[] val = str.toCharArray(); /* avoid getfield opcode */

		while ((st < len) && (val[off + len - 1] <= ' ')) {
			len--;
		}
		
		return ((st > 0) || (len < str.length())) ? str.substring(st, len) : str;
	}

Initial URL

Initial Description

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

Initial Title

Trim trailing whitespace

Initial Tags

Initial Language

Java

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