Syntax error Check that the String does not contain certain characters in Java

Check that the String does not contain certain characters in Java



Let’s say the following is our string with special characters.

String str = "test*$demo";

Check for the special characters.

Pattern pattern = Pattern.compile("[^A-Za-z0-9]");
Matcher match = pattern.matcher(str);
boolean val = match.find();

Now, if the bool value “val” is true, that would mean the special characters are in the string.

if (val == true)
System.out.println("Special characters are in the string.");

Example

 Live Demo

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Demo {
   public static void main(String []args) {
      String str = "test*$demo";
      System.out.println("String: "+str);
      Pattern pattern = Pattern.compile("[^A-Za-z0-9]");
      Matcher match = pattern.matcher(str);
      boolean val = match.find();
      if (val == true)
         System.out.println("Special characters are in the string.");
      else
         System.out.println("Special characters are not in the string.");
   }
}

Output

String: test*$demo
Special characters are in the string.

The following is another example with a different input.

Example

 Live Demo

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Demo {
   public static void main(String []args) {
      String str = "testdemo";
      System.out.println("String: "+str);
      Pattern pattern = Pattern.compile("[^A-Za-z0-9]");
      Matcher match = pattern.matcher(str);
      boolean val = match.find();
      if (val == true)
         System.out.println("Special characters are in the string.");
      else
      System.out.println("Special characters are not in the string.");
   }
}

Output

String: testdemo
Special characters are not in the string...
Updated on: 2020-06-27T06:09:03+05:30

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