In Java, determine whether a string is "both numeric" and "contains numbers" and "intercepts numbers"

In JavaScript there is a method isdigit () used to determine whether a string is a number, in the Java string processing method does not have such a method, it is often necessary to use, so the Internet search, sorted out two with regular expression matching method, as follows:

//determines whether a string is numeric Public Booleanisdigit (String strnum) {returnStrnum.matches ("[0-9]{1,}"); }    //determines whether a string is numeric Public Booleanisdigit (String strnum) {pattern pattern= Pattern.compile ("[0-9]{1,}"); Matcher Matcher=Pattern.matcher ((charsequence) strnum); returnmatcher.matches (); }//Intercept Numbers Publicstring Getnumbers (string content) {pattern pattern= Pattern.compile ("\\d+"); Matcher Matcher=pattern.matcher (content);  while(Matcher.find ()) {returnMatcher.group (0); }      return""; }    //Intercept non-digital Publicstring Splitnotnumber (string content) {pattern pattern= Pattern.compile ("\\d+"); Matcher Matcher=pattern.matcher (content);  while(Matcher.find ()) {returnMatcher.group (0); }      return""; }
  //determines whether a string contains a number Public Booleanhasdigit (String content) {BooleanFlag =false; Pattern P= Pattern.compile (". *\\d+.*"); Matcher m=p.matcher (content); if(M.matches ()) {flag=true; }    returnFlag;}

Three ways to determine whether a string is a number in Java:

1. Functions with Java

     Public Static Boolean isnumeric (String str) {        for (int i = str.length ();-I >= 0 ;) {            if (!  Character.isdigit (Str.charat (i))) {                returnfalse;            }        }         return true ;    }

2. Using regular expressions

     Public Static Boolean isnumeric (String str) {        = Pattern.compile ("[0-9]*");         return pattern.matcher (str). matches ();    }

3. Using ASCII code

     Public Static Boolean isnumeric (String str) {        for (int i = str.length ();-I >= 0 ;) {            int chr = Str.charat (i);             if (Chr < | | chr >)                 return false ;        }         return true ;    }

In Java, determine whether a string is "both numeric" and "contains numbers" and "intercepts numbers"