Java String replace using regular expressions

Question

As part of a project for school  I need to replace a string from the form   5   x 3 - 6   x 1   1   to something like   5x lt sup gt 3 lt  sup gt  - 6x lt sup gt 1 lt  sup gt    1   I believe this can be done with regular expressions  but I don t know how to do it yet   Can you lend me a hand    P S  The actual assignment is to implement a Polynomial Processing Java application  and I m using this to pass polynomial toString   from the model to the view  and I want do display it using html tags in a pretty way

User · Answer

str replaceAll       0-9        lt sup gt  1 lt  sup gt

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String input    hello I m a java dev     no job experience needed     senior software engineer     java job available for senior software engineer    String fixedInput   input replaceAll   java job senior      lt b gt  1 lt  b gt

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Take a look at antlr4   It will get you much farther along in creating a tree structure than regular expressions alone   https   github com antlr grammars-v4 tree master calculator   calculator g4 contains the grammar you need   In a nutshell  you define the grammar to parse an expression  use antlr to generate java code  and add callbacks to handle evaluation when the tree is being built

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Try this  may not be the best way  but it works  String str    5   x 3 - 6   x 1   1   str   str replaceAll    x    d     s        s      w             d        1 3 lt sup gt  5 lt  sup gt     System out println str

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import java util regex PatternSyntaxException          d      x      d          Options    and   match at line breaks        Match the regular expression below and capture its match into backreference number 1       d           Match the character         literally                 Between zero and one times  as many times as possible  giving back as needed  greedy              Match a single digit 0  9    d             Between one and unlimited times  as many times as possible  giving back as needed  greedy           Match the character         literally          Match the character         literally           Match the characters     x    literally    x      Match the character         literally           Match the regular expression below and capture its match into backreference number 2       d           Match the character         literally                 Between zero and one times  as many times as possible  giving back as needed  greedy              Match a single digit 0  9    d             Between one and unlimited times  as many times as possible  giving back as needed  greedy        try       String resultString   subjectString replaceAll    m      d       x        d       1x lt sup gt  2 lt  sup gt       catch  PatternSyntaxException ex           Syntax error in the regular expression   catch  IllegalArgumentException ex           Syntax error in the replacement text  unescaped   signs     catch  IndexOutOfBoundsException ex           Non-existent backreference used the replacement text

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If this is for any general math expression and parenthetical expressions are allowed  it will be very difficult  perhaps impossible  to do this with regular expressions   If the only replacements are the ones you showed  it s not that hard to do  First strip out   s  then use capturing like Can Berk G  der showed to handle the   s

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Try this   String str    5   x 3 - 6   x 1   1   String replacedStr   str replaceAll        d       lt sup gt   1 lt  sup gt       Be sure to import java util regex

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What is your polynomial  If you re  processing  it  I m envisioning some sort of tree of sub-expressions being generated at some point  and would think that it would be much simpler to use that to generate your string than to re-parse the raw expression with a regex   Just throwing a different way of thinking out there  I m not sure what else is going on in your app

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class Replacement        public static void main String args                  String Main    5   x 3 - 6   x 1   1           String replaced   Main replaceAll    m      d       x        d       1x lt sup gt  2 lt  sup gt             System out println replaced

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You ll want to look into capturing in regex to handle wrapping the 3 in  3

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5   x 3 - 6   x 1   1  replaceAll    W      W       replaceAll        d      lt sup gt  1 lt  sup gt       please note that joining both replacements in a single regex replacement would be a bad choice because more general expressions such as x 3 - 6   x would fail

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private String removeScript String content        Pattern p   Pattern compile   lt script   gt    gt       lt  script gt                Pattern DOTALL   Pattern CASE INSENSITIVE       return p matcher content  replaceAll

[java] Java; String replace (using regular expressions)?

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