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What is the StringUtils.stripToNull method in Java?

abhilash

Grokking Modern System Design Interview for Engineers & Managers

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Overview

In Java, stripToNull() is a static method of the StringUtils class that is used to strip all the leading and trailing whitespace from the given string. The method returns null if the resultant string is empty ("") after the strip.

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>

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

We can import the StringUtils class as follows:


import org.apache.commons.lang3.StringUtils;

Syntax


public static String stripToNull(final String str)

Parameters

This method takes the parameter, final String str, which is the string to be stripped.

Return value

This method returns a new string with all the leading and trailing whitespace removed from the input string.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>test</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>

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

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.1</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <transformer
                                        implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>Main</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

Explanation

There are four examples used in the code, explained one by one in this section.

Example 1

  • string - " 543234asfg "

The method returns 543234asfg with all the leading and trailing whitespaces removed from the input string.

Example 2

  • string - ""

The method returns null, as the input string is empty.

Example 3

  • string - null

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

Example 4

  • string - " "

The method returns null, as the resultant string after the strip is an empty string.

RELATED TAGS

java
stringutils
striptonull
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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