How do I check whether input string contains any spaces

Question

I have a input dialog that asks for XML element name  and I want to check it to see if it has any spaces   can I do something like name matches

User · Accepted Answer

Why use a regex   name contains        That should work just as well  and be faster

User · Answer

If you will use Regex  it already has a predefined character class   S  for any non-whitespace character    str matches    S      tells you if this is a string of at least one character where all characters are non-whitespace

User · Answer

if  str indexOf       gt   0    would be  slightly  faster

User · Answer

To check if a string does not contain any whitespaces  you can use string matches  quot    S   quot    Example   quot name quot         - gt  true  quot    quot           - gt  false  quot name xxname quot  - gt  false

User · Answer

You can use this code to check whether the input string contains any spaces  public static void main String  args        Scanner sc new Scanner System in       System out println  quot enter the string    quot        String s1 sc nextLine        int l s1 length        int count 0      for int i 0 i lt l i                  char c s1 charAt i           if c                         System out println  quot spaces are in the position of  quot  i           System out println count                       else                   System out println  quot no spaces are there quot

User · Answer

string name    Paul Creasey   if  name contains

User · Answer

A simple answer  along similar lines to the previous ones is   str matches      s        The first      says that there can be zero or more instances of any character in front of the space   The    s  says it must contain any whitespace character  The last      says there can be zero or more instances of any character after the space    When you put all those together  this returns true if there are one or more whitespace characters anywhere in the string    Here is a simple test you can run to benchmark your solution against   boolean containsWhitespace String str       return str matches      s         String   testStrings     test     test    te st    test     te   st                              t e s t               ttest    for  String eachString   testStrings            System out println   Does       eachString       contain whitespace                                    containsWhitespace eachString

User · Answer

This is tested in android 7 0 up to android 10 0 and it works  Use these codes to check if string contains space spaces may it be in the first position  middle or last    name   firstname getText   toString      name is the variable that holds the string value   Pattern space   Pattern compile    s      Matcher matcherSpace   space matcher name    boolean containsSpace   matcherSpace find      if constainsSpace    true       string contains space     else      string does not contain any space

User · Answer

If you really want a regex  you can use this one   str matches        t         In the sense that everything matching this regex is not a valid xml tag name   if str matches        t               print  the input string is not valid

User · Answer

You can use regex      s    Example program to count number of spaces  Java 9 and above  import java util regex Matcher  import java util regex Pattern   public class Main     public static void main String   args         Pattern pattern   Pattern compile  quot   s quot   Pattern CASE INSENSITIVE               Matcher matcher   pattern matcher  quot stackoverflow is a good place to get all my answers quot                 long matchCount   matcher results   count             if matchCount  gt  0         System out println  quot Match found  quot    matchCount    quot  times  quot                   else        System out println  quot Match not found quot                   For Java 8 and below you can use matcher find   in a while loop and increment the count  For example  int count   0  while  matcher find        count

[java] How do I check whether input string contains any spaces?

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