What is StringUtils.isAlphanumeric in Java?

Overview

isAlphanumeric() is a static method of the StringUtils class that is used to check if the given string only contains Unicode letters or digits. The method returns false if the string contains Unicode symbols other than Unicode letters and digits.

  • The method returns false if the input string is null.
  • The method returns false if the input string is empty.

How to import StringUtils

The definition of StringUtils can be found in the Apache Commons Lang package, which we can add to the Maven project by adding the following dependency to the pom.xml file.

<dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.12.0</version>
</dependency>

For other versions of the commons-lang package, refer to the Maven Repository.

You can import the StringUtils class as follows.

import org.apache.commons.lang3.StringUtils;

Syntax

public static boolean isAlphanumeric(final CharSequence cs)

Parameters

  • final CharSequence cs: the character sequence/string to check.

Return value

This method returns true if the string is not null and only contains Unicode digits or letters; otherwise, it returns false.

Code

import org.apache.commons.lang3.StringUtils;
public class Main {
    public static void main(String[] args) {
        String s = "543234asfg";
        System.out.printf("The output of StringUtils.isAlphanumeric() for the string - '%s' is %s", s, StringUtils.isAlphanumeric(s));
        System.out.println();
        s = "";
        System.out.printf("The output of StringUtils.isAlphanumeric() for the string - '%s' is %s", s, StringUtils.isAlphanumeric(s));
        System.out.println();
        s = null;
        System.out.printf("The output of StringUtils.isAlphanumeric() for the string - '%s' is %s", s, StringUtils.isAlphanumeric(s));
        System.out.println();
        s = "    \n\t";
        System.out.printf("The output of StringUtils.isAlphanumeric() for the string - '%s' is %s", s, StringUtils.isAlphanumeric(s));
        System.out.println();
        s = "hello-educative";
        System.out.printf("The output of StringUtils.isAlphanumeric() for the string - '%s' is %s", s, StringUtils.isAlphanumeric(s));
        System.out.println();
    }
}

Output

The output of the code will be as follows.

The output of StringUtils.isAlphanumeric() for the string - '543234asfg' is true
The output of StringUtils.isAlphanumeric() for the string - '' is false
The output of StringUtils.isAlphanumeric() for the string - 'null' is false
The output of StringUtils.isAlphanumeric() for the string - '    
	' is false
The output of StringUtils.isAlphanumeric() for the string - 'hello-educative' is false

Explanation

Example 1

  • string - "543234asfg"

The method returns true, as the string only contains Unicode digits and letters.

Example 2

  • string - ""

The method returns false, as the string is empty.

Example 3

  • string - null

The method returns false, as the string points to a null reference.

Example 4

  • string - " \n\t"

The method returns false, as the string contains whitespace characters that are not Unicode letters or digits.

Example 5

  • string - "hello-educative"

The method returns false, as the string contains Unicode letters with other Unicode symbols, such as -.

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