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Pattern pattern() method in Java with examples
The java.util.regex package of java provides various classes to find particular patterns in character sequences. The pattern class of this package is a compiled representation of a regular expression.
The pattern() method of the Pattern class fetches and returns the regular expression in the string format, using which the current pattern was compiled.
Example 1
import java.util.regex.Pattern;
public class PatternExample {
public static void main(String[] args) {
String date = "12/09/2019";
String regex = "^(1[0-2]|0[1-9])/(3[01]|[12][0-9]|0[1-9])/[0-9]{4}$";
//Creating a pattern object
Pattern pattern = Pattern.compile(regex);
if(pattern.matcher(date).matches()) {
System.out.println("Date is valid");
} else {
System.out.println("Date is not valid");
}
//Retrieving the regular expression of the current pattern
String regularExpression = pattern.pattern();
System.out.println("Regular expression: "+regularExpression);
}
}Output
Date is valid
Regular expression: ^(1[0-2]|0[1-9])/(3[01]|[12][0-9]|0[1-9])/[0-9]{4}$Example 2
public class PatternExample {
public static void main(String[] args) {
String input = "Hi my id is 056E1563";
//Regular expression using groups
String regex = "(.*)?(\d+)";
//Creating a pattern object
Pattern pattern = Pattern.compile(regex);
if(pattern.matcher(input).matches()) {
System.out.println("Match found");
} else {
System.out.println("Match not found");
}
//Retrieving the regular expression of the current pattern
String regularExpression = pattern.pattern();
System.out.println("Regular expression: "+regularExpression);
}
}Output
Match found Regular expression: (.*)?(\d+)
Updated on: 20-Nov-2019
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