Check if a String contains numbers Java

Question

I m writing a program where the user enters a String in the following format     What is the square of 10      I need to check that there is a number in the String  and then extract just the number   If i use  contains    d    or  contains   0-9      the program can t find a number in the String  no matter what the input is  but  matches    d   will only work when there is only numbers    What can I use as a solution for finding and extracting

User · Answer

You can try this  String text    ddd123 0114cc       String numOnly   text replaceAll    p Alpha            try           double numVal   Double valueOf numOnly           System out println text    contains numbers          catch  NumberFormatException e           System out println text   not contains numbers

User · Answer

If you want to extract the first number out of the input string  you can do- public static String extractNumber final String str                             if str    null    str isEmpty    return  quot  quot            StringBuilder sb   new StringBuilder        boolean found   false      for char c   str toCharArray             if Character isDigit c                sb append c               found   true            else if found                  If we already found a digit before and this char is not a digit  stop looping             break                                           return sb toString       Examples   For input  quot 123abc quot   the method above will return 123  For  quot abc1000def quot   1000  For  quot 555abc45 quot   555  For  quot abc quot   will return an empty string

User · Answer

Below code snippet will tell whether the String contains digit or not str matches  quot     d   quot   or str matches    0-9      For example String str    quot abhinav123 quot    str matches  quot     d   quot   or str matches    0-9      will return true   str    quot abhinav quot    str matches  quot     d   quot   or str matches    0-9      will return false

User · Answer

ASCII is at the start of UNICODE  so you can do something like this    x  gt   97  amp  amp  x  lt   122      x  gt   65  amp  amp  x  lt   90     97     a  and 65    A    I m sure you can figure out the other values

User · Answer

As you don t only want to look for a number but also extract it  you should write a small function doing that for you  Go letter by letter till you spot a digit  Ah  just found the necessary code for you on stackoverflow  find integer in string  Look at the accepted answer

User · Answer

matches      d      only works for numbers but not other symbols like    or   etc

User · Answer

I could not find a single pattern correct  Please follow below guide for a small and sweet solution   String regex           d              Pattern pattern   Pattern compile regex   String msg    What is the square of 10    boolean containsNumber   pattern matcher msg  matches

User · Answer

I think it is faster than regex    public final boolean containsDigit String s        boolean containsDigit   false       if  s    null  amp  amp   s isEmpty              for  char c   s toCharArray                  if  containsDigit   Character isDigit c                     break                                     return containsDigit

User · Answer

The solution I went with looks like this   Pattern numberPat   Pattern compile    d     Matcher matcher1   numberPat matcher line    Pattern stringPat   Pattern compile  What is the square of   Pattern CASE INSENSITIVE   Matcher matcher2   stringPat matcher line    if  matcher1 find    amp  amp  matcher2 find          int number   Integer parseInt matcher1 group                             pw println number     squared        number   number        I m sure it s not a perfect solution  but it suited my needs  Thank you all for the help

User · Answer

public String hasNums String str            char   nums      0    1    2    3    4    5    6    7    8    9             char   toChar   new char str length             for  int i   0  i  lt  str length    i                  toChar i    str charAt i               for  int j   0  j  lt  nums length  j                      if  toChar i     nums j     return str                                    return  None

User · Answer

Pattern p   Pattern compile     A-Z    0-9      Matcher m   p matcher  TEST 123    boolean b   m find    System out println b

User · Answer

As I was redirected here searching for a method to find digits in string in Kotlin language  I ll leave my findings here for other folks wanting a solution specific to Kotlin  Finding out if a string contains digit  val hasDigits   sampleString any   it isDigit      Finding out if a string contains only digits  val hasOnlyDigits   sampleString all   it isDigit      Extract digits from string  val onlyNumberString   sampleString filter   it isDigit

User · Answer

The code below is enough for  Check if a String contains numbers in Java   Pattern p   Pattern compile    0-9      Matcher m   p matcher  Here is ur string     if m find         System out println  Hello   m find

User · Answer

Try the following pattern    matches   a-zA-Z     d

User · Answer

try this   str matches      d

User · Answer

s s replaceAll    a-zA-Z        replaces all alphabets  s s replaceAll    0-9         replaces all numerics  if you do above two replaces you will get all special charactered string  If you want to extract only integers from a String s s replaceAll    0-9         If you want to extract only Alphabets from a String s s replaceAll    a-zA-Z         Happy coding

[java] Check if a String contains numbers Java

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