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What is StringUtils.isEmpty in Java?

abhilash

Grokking Modern System Design Interview for Engineers & Managers

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isEmpty() is a static method of the StringUtils class that is used to check if a given string is empty or not.

If a string satisfies any of the criteria below, then the string is considered to be empty.

  1. The length of the string is zero.
  2. The string points to a null reference.

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 isEmpty(final CharSequence cs)

Parameters

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

Return value

This method returns true if the string is null or the length of the string is zero; otherwise, it returns false.

Code

import org.apache.commons.lang3.StringUtils;
public class Main {
public static void main(String[] args) {
String s = "543234";
System.out.printf("The output of StringUtils.isEmpty() for the string - '%s' is %s", s, StringUtils.isEmpty(s));
System.out.println();
s = "";
System.out.printf("The output of StringUtils.isEmpty() for the string - '%s' is %s", s, StringUtils.isEmpty(s));
System.out.println();
s = null;
System.out.printf("The output of StringUtils.isEmpty() for the string - '%s' is %s", s, StringUtils.isEmpty(s));
System.out.println();
}
}

Output

The output of the code will be as follows.

The output of StringUtils.isEmpty() for the string - '543234' is false
The output of StringUtils.isEmpty() for the string - '' is true
The output of StringUtils.isEmpty() for the string - 'null' is true

Explanation

Example 1

  • string - "543234"

The method returns false because the string is not null and has a length greater than zero.

Example 2

  • string - ""

The method returns true because the length of the string is zero.

Example 3

  • string - null

The method returns true because the string points to a null reference.

RELATED TAGS

java
communitycreator

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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