Pattern pattern() method in Java with Examples

The pattern() method of the Pattern class in Java is used to get the regular expression which is compiled to create this pattern. We use a regular expression to create the pattern and this method used to get the same source expression. 

Syntax:

public String pattern()

Parameters: This method does not accepts anything as parameter. 

Return Value: This method returns the pattern’s source regular expression. 

Below programs illustrate the pattern() method: 

Program 1:

Java

// Java program to demonstrate
// Pattern.pattern() method

import java.util.regex.*;

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

        // create a REGEX String
        String REGEX = "(.*)(for)(.*)?";

        // create the string
        // in which you want to search
        String actualString = "code of Machine";

        // create pattern
        Pattern pattern1 = Pattern.compile(REGEX);

        // find the regular expression of pattern
        String RegularExpression = pattern1.pattern();

        System.out.println("Pattern's RegularExpression = "
                           + RegularExpression);
    }
}

Output:

Pattern's RegularExpression = (.*)(for)(.*)?

Program 2:

Java

// Java program to demonstrate
// Pattern.pattern method

import java.util.regex.*;

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

        // create a REGEX String
        String REGEX = "(.*)(ee)(.*)?";

        // create the string
        // in which you want to search
        String actualString = "geeks";

        // create pattern
        Pattern pattern1 = Pattern.compile(REGEX);

        // find the regular expression of pattern
        String RegularExpression = pattern1.pattern();

        System.out.println("Pattern's RegularExpression = "
                           + RegularExpression);
    }
}

Output:

Pattern's RegularExpression = (.*)(ee)(.*)?

Program 3:

Java

import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class GFG {

    public static void main(String[] args)
    {
        String input1
            = "The quick brown fox jumps over the lazy dog";
        String input2
            = "The quick red fox jumps over the lazy dog";
        String regex = "(?i)the";
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher1 = pattern.matcher(input1);
        Matcher matcher2 = pattern.matcher(input2);
        while (matcher1.find()) {
            System.out.println("Match 1: "
                               + matcher1.group());
        }
        while (matcher2.find()) {
            System.out.println("Match 2: "
                               + matcher2.group());
        }
    }
}

Output

Match 1: The
Match 1: the
Match 2: The
Match 2: the