In this article, we are able to discover ways to make Java Regular Expression case-insensitive in Java. Java Regular Expression is used to find, match, and extract facts from man or woman sequences. Java Regular Expressions are case-touchy through default. But with the assist of Regular Expression, we are able to make the Java Regular Expression case-insensitive. There are approaches to make Regular Expression case-insensitive:

1. Using CASE_INSENSITIVE flag
2. Using modifier

1. Using CASE_INSENSITIVE flag: The compile method of the Pattern class takes the CASE_INSENSITIVE flag along with the pattern to make the Expression case-insensitive. Below is the implementation:

JAVA:

// Java program demonstrate How to make Java
// Regular Expression case insensitive in Java
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class GFG {
	public static void main(String[] args)
	{

		// String
		String str = "From GFG class. Welcome to gfg.";

		// Create pattern to match along
		// with the flag CASE_INSENSITIVE
		Pattern patrn = Pattern.compile(
			"gfg", Pattern.CASE_INSENSITIVE);

		// All metched patrn from str case
		// insensitive or case sensitive
		Matcher match = patrn.matcher(str);

		while (match.find()) {
			// Print matched Patterns
			System.out.println(match.group());
		}
	}
}

Output

GFG
gfg

2. Using modifier: The ” ?i “ modifier used to make a Java Regular Expression case-insensitive. So to make the Java Regular Expression case-insensitive we byskip the sample at the side of the ” ?i ” modifier that makes it case-insensitive. Below is the implementation:

JAVA

// Java program demonstrate How to make Java
// Regular Expression case insensitive in Java
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class GFG {
	public static void main(String[] args)
	{

		// String
		String str = "From GFG class. Welcome to gfg.";

		// Create pattern to match along
		// with the ?i modifier
		Pattern patrn = Pattern.compile("(?i)gfg");

		// All metched patrn from str case
		// insensitive or case sensitive
		Matcher match = patrn.matcher(str);

		while (match.find()) {
			// Print matched Patterns
			System.out.println(match.group());
		}
	}
}

Output

GFG
gfg