How to Convert a Java String Against a Pattern Regex?

Regular expressions, or “regex,” are an effective tool in Java programming for checking texts against a given pattern. This post will walk you through the process of utilizing regular expressions to validate a Java text against a pattern.

Prerequisites:

• String in Java
• Regular Expressions in Java

Convert Java String against Pattern Regex

Format or String structure using a regular expression pattern is used here. The Matcher class is responsible for comparing the pattern with the input string. If the full string fits the pattern, the Matcher class’s matches() function returns true.

Java

// Java Program to Convert
// Java String against Pattern Regex
import java.util.regex.*;

// Driver Class
public class Temp {

    // Method to check pattern
    static void checkPattern(String testString, String regex) {
        // Split the string based on whitespaces
        String[] words = testString.split("\\s+");

        // Compile the pattern
        Pattern pattern = Pattern.compile(regex);

        for (String word : words) {
            Matcher matcher = pattern.matcher(word);

            // Check if the string matches the pattern
            if (!matcher.matches()) {
                System.out.print(word + " ");
            }
        }

        System.out.println();
    }

    // Main Function
    public static void main(String[] args) {
        String testString = "I am in GFG. GFG is a good company and I like to work in it";

        // Define a simple regex pattern
        // Regex for GFG
        String regex = ".*\\bGFG\\b.*";

        // Call the checkPattern method
        checkPattern(testString, regex);
    }
}

Output

I am in is a good company and I like to work in it