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What is StringUtils.containsIgnoreCase in Java?

abhilash

Grokking Modern System Design Interview for Engineers & Managers

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What is containsIgnoreCase?

containsIgnoreCase is a static method of the StringUtils class that checks whether a given string contains the complete search string as a whole, while ignoring the case considerations.


The comparison is case-insensitive in nature. Refer to What is StringUtils.contains in Java? for case-sensitive comparison.

Add Apache Common Langs package

StringUtils is defined in the Apache Commons Lang package. To add Apache Commons Lang to the Maven project, add 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.

How to import StringUtils

You can import the StringUtils class as follows.


import org.apache.commons.lang3.StringUtils;

Syntax


public static boolean containsIgnoreCase(final CharSequence str, final CharSequence searchStr)

Parameters

  • final CharSequence str: the character sequence to search in.

  • final CharSequence searchStr: the search sequence to search for.

Return value

The function returns true if the character sequence contains a complete search sequence, ignoring the case considerations. Otherwise, it returns false.

Code

Example 1

  • search string = "AbC"
  • string = "aBBbcCcAAaCcB"

Although "string" contains the same individual characters of "search string," it doesn’t contain the complete "search string" (ignoring the case considerations).

Hence, StringUtils.containsIgnoreCase would return false.

Example 2

  • search string = "aBC"
  • string = "AbCdefghti"

Since "string" contains the complete "search string" (ignoring the case considerations), StringUtils.containsIgnoreCase would return true.

import org.apache.commons.lang3.StringUtils;
public class Main{
public static void main(String[] args){
String characterSequence = "aBBbcCcAAaCcB";
String searchString = "AbC";
System.out.println(StringUtils.containsIgnoreCase(characterSequence, searchString));
characterSequence = "AbC**defghti";
searchString = "aBC";
System.out.println(StringUtils.containsIgnoreCase(characterSequence, searchString));
}
}

Output

The output of the code will be as follows.

false
true

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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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