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.
null reference.StringUtilsThe 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;
public static boolean isEmpty(final CharSequence cs)
final CharSequence cs: the character sequence/string to check.This method returns true if the string is null or the length of the string is zero; otherwise, it returns false.
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();}}
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
string - "543234"The method returns false because the string is not null and has a length greater than zero.
string - ""The method returns true because the length of the string is zero.
string - nullThe method returns true because the string points to a null reference.