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Posix character classes p{Alnum} Java regex
This class matches alpha numeric characters.
Example
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class AlphanumericExample {
public static void main(String args[]) {
//Reading String from user
System.out.println("Enter a string");
Scanner sc = new Scanner(System.in);
String input = sc.nextLine();
//Regular expression
String regex = "[\p{Alnum}]";
//Compiling the regular expression
Pattern pattern = Pattern.compile(regex);
//Retrieving the matcher object
Matcher matcher = pattern.matcher(input);
int count = 0;
while(matcher.find()) {
count++;
}
System.out.println("Number of alphanumeric characters: "+count);
}
}Output 1
Enter a string sample 123 Number of digits: 9
Output 2
Enter a string @$#%&&#* Number of alphanumeric characters: 0
Example
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main( String args[] ) {
//Regular expression to match lower case letters
String regex = "^\p{Alnum}+$";
//Getting the input data
Scanner sc = new Scanner(System.in);
System.out.println("Enter 5 input strings: ");
String input[] = new String[5];
for (int i=0; i<5; i++) {
input[i] = sc.nextLine();
}
//Creating a Pattern object
Pattern p = Pattern.compile(regex);
System.out.println("Strings with only alphanumeric characters: ");
for(int i=0; i<5;i++) {
//Creating a Matcher object
Matcher m = p.matcher(input[i]);
if(m.matches()) {
System.out.println(m.group());
}
}
}
}Output
Enter 5 input strings: hello 1234 243test ##$$@ *** Strings with only alphanumeric characters: hello 1234 243test
Updated on: 21-Feb-2020
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