Check if the String contains only unicode letters or digits in Java

To check whether a String contains only unicode letters or digits in Java, we use the isLetterOrDigit() method and charAt() method with decision-making statements.

The isLetterOrDigit(char ch) method determines whether the specific character (Unicode ch) is either a letter or a digit. It returns a boolean value, either true or false.

Declaration −The java.lang.Character.isLetter() method is declared as follows −

public static boolean isLetter(char ch)

The charAt() method returns a character value at a given index. It belongs to the String class in Java. The index must be between 0 to length()-1.

Declaration −The java.lang.String.charAt() method is declared as follows −

public char charAt(int index)

Let us see a program in Java to check whether a String contains only Unicode letters or digits.

Example

public class Example {
   boolean check(String s) {
      if (s == null) // checks if the String is null {
         return false;
      }
      int len = s.length();
      for (int i = 0; i 
Output
String 10@4 has only unicode letters or digits : false
String 13y4 has only unicode letters or digits : true
String 1000 has only unicode letters or digits : true
String abcd has only unicode letters or digits : true