CASE_INSENSITIVE field and example in Java

The CASE_INSENSITIVE field of the Pattern class matches characters regardless of case. When this value is used ascompile()when the flag value of the method is used, and if regular expression search is used to search for characters, characters in both cases will match.

Note-By default, this flag only matches ASCII characters

Example1

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class CASE_INSENSITIVE_Example {
　　　public static void main( String args[] ) {
　　　　　　Scanner sc = new Scanner(System.in);
　　　　　　System.out.println("Enter input data: ");
　　　　　　String input = sc.nextLine();
　　　　　　System.out.println("Enter required character: ");
　　　　　　char ch = sc.next().toCharArray()[0];
　　　　　　//The regular expression is used to find the required character
　　　　　　String regex = "["+ch+"]";
　　　　　　//Compiling the regular expression
　　　　　　Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
　　　　　　//Retrieving the matcher object
　　　　　　Matcher matcher = pattern.matcher(input);
　　　　　　int count = 0;
　　　　　　while (matcher.find()) {
　　　　　　　　　count++;
　　　　　　{
　　　　　　System.out.println("The letter ",+ch+"occurred"+count+"times in the given text (irrespective of case)");
　　　{
{

Output result

Enter input data:
oldtoolbag.com originated from the idea that there exists a class　
of readers who respond better to online content and prefer to learn　
new skills at their own pace from the comforts of their drawing rooms.
Enter required character:
T
The letter T occurred　20 times in the given text (irrespective of case)

Example2

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class VerifyBoolean {
　　　public static void main(String args[]) {
　　　　　　Scanner sc = new Scanner(System.in);
　　　　　　System.out.println("Enter a string value: ");
　　　　　　String str = sc.next();
　　　　　　Pattern pattern = Pattern.compile("true|false", Pattern.CASE_INSENSITIVE);
　　　　　　Matcher matcher = pattern.matcher(str);
　　　　　　if(matcher.matches()){
　　　　　　　　　System.out.println("Given string is a boolean type");
　　　　　　} else {
　　　　　　　　　System.out.println("Given string is not a boolean type");
　　　　　　{
　　　{
{

Output1

Enter a string value:
true
Given string is a boolean type

Output2

Enter a string value:
false
Given string is a boolean type

Output3

Enter a string value:
hello
Given string is not a boolean type