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Program to find whether a string is alphanumeric.
Any word that contains numbers and letters is known as alphanumeric. The following regular expression matches the combination of numbers and letters.
"^[a-zA-Z0-9]+$";
The matches method of the String class accepts a regular expression (in the form of a String) and matches it with the current string in case the match this method returns true else it returns false.
Therefore, to find whether a particular string contains alpha-numeric values −
- Get the string.
- Invoke the match method on it bypassing the above mentioned regular expression.
- Retrieve the result.
Example 1
import java.util.Scanner;
public class AlphanumericString {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter input string: ");
String input = sc.next();
String regex = "^[a-zA-Z0-9]+$";
boolean result = input.matches(regex);
if(result) {
System.out.println("Given string is alpha numeric");
} else {
System.out.println("Given string is not alpha numeric");
}
}
}Output
Enter input string: abc123* Given string is not alpha numeric
Example 2
You can also compile a regular expression and match it with a particular string using the classes and methods (APIs) of the java.util.regex package. The following program is written using these APIs and it verifies whether a given string is alpha-numeric.
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Test {
public static void main( String args[] ) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter input string: ");
String input = sc.nextLine();
String regex = "^[a-zA-Z0-9]+$";
String data[] = input.split(" ");
//Creating a pattern object
Pattern pattern = Pattern.compile(regex);
for (String ele : data){
//creating a matcher object
Matcher matcher = pattern.matcher(ele);
if(matcher.matches()) {
System.out.println("The word "+ele+": is alpha numeric");
} else {
System.out.println("The word "+ele+": is not alpha numeric");
}
}
}
}Output
Enter input string: hello* this$ is sample text The word hello*: is not alpha numeric The word this$: is not alpha numeric The word is: is alpha numeric The word sample: is alpha numeric The word text: is alpha numeric
Updated on: 21-Nov-2019
2K+ Views
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