What is the StringUtils.substring() method in Java?

Overview

In Java, substring() is a static method of the StringUtils class that returns the string between the given start and end index. Negative start and end index positions can be used to specify offsets relative to the end of the string.

How to import StringUtils

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 substring(final String str, int start, int end)

Parameters

  • str: This is the given string from which the substring has to be extracted.
  • start: This is the starting index.
  • end: This is the ending index.

Return value

This method returns a substring.

Example

<?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

The Maven dependency for StringUtils is included in the pom.xml file: Main.java

  • Line 1: We import the StringUtils class.
  • Line 6: We define the text or the string called text.
  • Line 7: We define the starting index called start.
  • Line 8: We define the ending index called end.
  • Line 10: The substring between start and end is retrieved by invoking the substring() method.
  • Line 12: We define a negative value for end.
  • Line 13: The substring between start and end is retrieved by invoking the substring() method. As end is a negative value, the end offset is relative to the end of the string.

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