I've got some code that is going to chew up a lot of CPU and I wonder if there is going to be a quicker way than using pre-compiled regular expressions.
Stackoverflow should not be used to discuss which algorithm to use to achieve a task might be faster? Use String. That may not be the absolute "fastest" possible approach. But in general there's not much point in trying to compete with the people who write the language's "standard library" in terms of performance. I've written the tests that compare using regular expressions as per other answers against not using regular expressions. Tests done on a quad core OSX Interestingly using regular expressions turns out to be about times slower than manually iterating over a string.
Furthermore the isAlphanumeric2 function is marginally faster than isAlphanumeric. One supports the case where extended Unicode numbers are allowed, and the other is for when only standard ASCII numbers are allowed. A regex will probably be quite efficient, because you would specify ranges: [a-zA-Z]. Assuming the implementation code for regexes is efficient, this would simply require an upper and lower bound comparison for each range.
Here's basically what a compiled regex should do:. I don't see how your code could be more efficient than this, because every character will need to be checked, and the comparisons couldn't really be any simpler. Learn more. Fastest way to check a string is alphanumeric in Java [closed] Ask Question. Asked 7 years, 6 months ago. Active 9 months ago. Viewed 91k times. What is the fastest way to check that a String contains only alphanumeric characters.
Jacob Jacob Premature optimization? StephenC There is no code to show, I am asking what the best way is. JimGarrison Some people do have a propensity to do premature optimisation, so its good to raise the question.
Active Oldest Votes. C has a standard function for this. It appears Java does not. But there is a point. When you are executing code in a loop millions of times, and you can make it run 5 times faster, it can make a significant impact to your message processing time, and that impacts how many servers you might need for message processing. I believe that's overstating it. At best you're making one small aspect of the code 5 times faster. That may be worthwhile, iff your performance is actually being limited by that aspect.
It may well not be.Thanks letter for successful audit
For instance, if part of your message processing pipeline involves writing to a database or filesystem or doing any network comms, that's likely your limiting factor. There aren't many real-world cases where speeding up a regex check by 5x will actually speed up the application by 5x or anywhere close to 5x.In Theory, there is no difference between theory and practice. Originally posted by Alan Moore: Grant, converting digit sequences to numbers is the obvious approach, but it has a major flaw: what if the number is too large to be represented as an int or long?
The character-by-character approach also seems cleaner and more efficient to me. Well, your code is certainly thorough! I think it's overkill for the OP's requirements which, admittedly, are possibly not complete.How to remove the duplicates From String in java?
If your digit-strings are more than 20 digits, you'll need more than a long - although if I really wanted to worry about that, I'd probably just convert to using BigInteger for it, rather than rolling my own. But I think the real issue underlying this discussion is one of flawed design. Anytime I see code that wants to do more than one thing at a time, it suggests to me that I haven't stated the problem correctly.
Originally posted by Alan Moore: I did say I wrote it for my own use. And I'm sure the OP's stated requirements are incomplete; he didn't even say whether letters should be sorted case-sensitively or not. But this class should at least give him a good start on solving his problem. Originally posted by Alan Moore: I don't see this as trying to do more than one thing at a time; it's just another way of sorting strings.
Unless you're saying that, instead of using strings, the OP should create a custom data object with a string field and a numeric field. If that's an option, I agree it would be a better way to go. May need to add it to my toolbox, if you don't mind. Forum: Java in General. Ordering of AlphaNumeric No. I have data with mix number of digits and I like to sort them.
Somehow, the normal sorting process give me a not so desired result. Can anyone help? Its very Impotant for me. Grant Gainey. The problem is that you're trying to sort both lexicographically and numerically at the same time. If you interpret the strings as numbers, then it's clear that 2 comes before Your requirement needs it both ways.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.
If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. An alphanumeric comparator in Java, for comparing and sorting strings in a more human readable format.
It uses a combination of numeric and alphabetic comparisons to compare two strings. This class uses standard Java classes and is independent of any 3rd party libraries. Additionally this comparator uses java. A regular lexicographical sort, e. However using AlphaNumericComparatorthe list will be sorted in a more meaningful and readable way:.
Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. An alphanumeric comparator in Java to simplify comparison and sorting of strings in a more human readable format. Java Branch: master. Find file. Sign in Sign up.
Go back. Launching Xcode If nothing happens, download Xcode and try again. Latest commit Fetching latest commit…. Example 1 For given list of strings: file You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. New test case added. Mar 24, Aug 7, Mar 14, An alphanumeric comparison is a comparison of the single-byte character values of two operands.
Sort alphanumeric string with awareness of number using Java comparator
When one of the operands is neither class alphanumeric nor class alphabetic, that operand is processed as follows:. When the ZWB compiler option is in effect, the unsigned value of the integer operand is moved to the temporary data item. Alphanumeric comparisons are made with respect to the collating sequence of the character set in use as follows:.
The size of each operand is the total number of character positions in that operand; the size affects the result of the comparison. There are two cases to consider:. If all pairs of characters through the last pair evaluate as equal, the operands are equal.
If a pair of unequal characters is encountered, the characters are tested to determine their relative positions in the collating sequence. The operand that contains the character higher in the sequence is considered the greater operand. A standard comparison is any comparison that is not based on a locale. The standard comparison method depends on whether the operands to be compared are of equal length or unequal length.
If the operands are of unequal length, the comparison proceeds as though the shorter operand were padded on the right with appropriate space characters to make the operands of equal length. The comparison then proceeds according to the rules for the comparison of operands of equal length. If the operands are of equal length, the comparison proceeds by comparing corresponding character positions in the two operands, starting from the leftmost position, until either unequal characters are encountered or the rightmost character position is reached, whichever comes first.
The operands are determined to be equal if all corresponding characters are equal. The first-encountered unequal character in the operands is compared to determine the relation of the operands. The operand that contains the character with the higher collating value is the greater operand. Alphanumeric comparisons An alphanumeric comparison is a comparison of the single-byte character values of two operands. When one of the operands is neither class alphanumeric nor class alphabetic, that operand is processed as follows: A display floating-point data item is treated as though it were a data item of category alphanumeric, rather than as a numeric value.
A zoned decimal integer operand is treated as though it were moved to a temporary elementary data item of category alphanumeric with a length the same as the total number of digits in the numberaccording to the rules of the MOVE statement. Comparison then proceeds with the temporary data item of category alphanumeric. There are two cases to consider: Operands of equal size Characters in corresponding positions of the two operands are compared, beginning with the leftmost character and continuing through the rightmost character.
Operands of unequal size If the operands are of unequal size, the comparison is made as though the shorter operand were extended to the right with enough spaces to make the operands equal in size.
The higher collating value is determined using the hexadecimal value of characters. Standard comparison A standard comparison is any comparison that is not based on a locale. Parent topic: General relation conditions. Published: 30 November This example will show you how to allow only alphanumeric characters in a string using the a-zA-Z regular expression pattern. It also shows how to remove special characters from the string. The below given regular expression pattern can be used to check if the string contains only alphanumeric characters or not.
It fails to match the Unicode characters. If the application needs Unicode characters compatible pattern matching, then the following pattern should be used. A similar pattern can be used to remove unwanted characters from the string as well. We are going to use the following pattern to replace all special characters with the empty string. My name is RahimV and I have over 16 years of experience in designing and developing Java applications.
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A-Z - any character between A and Z. You may also like. Java split string by comma example 5 Min Read. Java split String into equal length substrings example 2 Min Read. Remove leading and trailing spaces from String in Java example 3 Min Read. Java split String by words example 3 Min Read. Convert int array to String in Java example 2 Min Read. Check if String starts with a number in Java example 2 Min Read. Java String keep only letters and numbers example 3 Min Read.
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Code Review Stack Exchange is a question and answer site for peer programmer code reviews. It only takes a minute to sign up. This code will generate a pseudorandom alphanumeric string of given length. I would welcome suggestions on how to make it more random. Beyond that, have I made any convention violations, Exception cases, and the like?
Also, is there any way to make it faster?
Generate a Random Alpha Numeric String
And related loops should have the "for" on the same line as this is a common coding convention. This doesn't have to be a double; instead, the random number can be generated as an integer to select which element from the array. Unless the random string is not random, I would not initialize the variables with sample data. I'd just leave them blank and then adjust the loop to always run at least once a do-while loop so that it becomes initialized. I would remove the inner if-statement and un-hardcode the values so it can work with strings with any size.
Applying these suggestions, it can be simplified to:. This approach is not optimal as the string is constantly being appended to, meaning that the string has to be re-copied every iteration. Java introduced Streams, which allows reading forever from certain generators.
Knowing this, we can read a stream of random numbers up until the string length that the user wants, and then get the character at the random string length:. StringBuilder is used to append the random character as it doesn't have to be re-copied for every loop iteration. I would either extract the random number generator into an extra methodor simply use new Random.
You could also make the method more generic by adding boundary parameters min, max. So you can reuse within other limitations.2002 lexus ls430 locations of fuses for car stereo
See: Math.Given two strings that can contain lower and uppercase alphabets, numbers and special characters like dots, blank spaces, commas, etc. Compare both strings considering only alphanumeric characters [a-b], [A-B] and  if they are equal or not. Since we have to compare only alphanumeric characters therefore whenever any other character is found simply ignore it by increasing iterator pointer.
For doing it simply take two integer variables i and j and initialize them by 0.Pushing someone away in a relationship
Now run a loop to compare each and every character of both strings. Compare one by one if the character is alphanumeric otherwise increase the value of i or j by one. Writing code in comment? Please use ide. Therefore both strings are equal.
Therefore both strings are not equal. CompareAlphanumericUtil str1, str2. String str2. String str1, str2. Function to check alphanumeric equality.
Length of first string. Length of second string. To check each and every character of both string. If the current character of the first string. If the current character of the second string. If current character matched. If not same, then return false. Function to print Equal or Unequal. CompareAlphanumericUtil str1, str2. ToCharArray .
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