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Java regex program to verify whether a String contains at least one alphanumeric character.
Following regular expression matches a string that contains at least one alphanumeric characters −
"^.*[a-zA-Z0-9]+.*$";
Where,
^.* Matches the string starting with zero or more (any) characters.
[a-zA-Z0-9]+ Matches at least one alpha-numeric character.
.*$ Matches the string ending with zero or more (ant) characters.
Example 1
import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { 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 = "^.*[a-zA-Z0-9]+.*$"; //Compiling the regular expression Pattern pattern = Pattern.compile(regex); //Retrieving the matcher object Matcher matcher = pattern.matcher(input); int count = 0; if(matcher.matches()) { System.out.println("Given string is valid"); } else { System.out.println("Given string is not valid"); } } }
Output 1
Enter a string ###test123$$$ Given string is valid
Output 2
Enter a string ####$$$$ Given string is not valid
Example 2
import java.util.Scanner; public class Example { public static void main(String args[]) { //Reading String from user System.out.println("Enter a string"); Scanner sc = new Scanner(System.in); String input = sc.nextLine(); //Regular expression String regex = "^.*[a-zA-Z0-9]+.*$"; boolean result = input.matches(regex); if(result) { System.out.println("Valid match"); }else { System.out.println("In valid match"); } } }
Output 1
Enter a string ###test123$$$ Valid match
Output 2
Enter a string ####$$$$ In valid match
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