A regular expression pattern in Java is defined using the Pattern class, which is a component of the java.util.regex package. But sometimes, we may wish to reset the internal state of the Pattern object or use it again with a different input string. This helps to improve efficiency in instances where pattern matching occurs often by avoiding the need to recreate the Pattern object numerous times.
Resetting the Pattern of a Regular Expression in Java
We may reset the internal state of the Pattern object in Java using the reset() method of the Pattern class. When we want to match against several input strings using the same Pattern object again, this is helpful.
Let’s look at a simple example to understand how to reset a regular expression’s pattern in Java:
// Java Program for Resetting the Pattern of a Regular Expression import java.util.regex.*;
// Driver Class public class PatternResetExample {
// Main FUnction
public static void main(String[] args)
{
// Create a Pattern object
// It matches one or more than one digits
Pattern pattern = Pattern.compile( "\\d+" );
// Create a Matcher object
Matcher matcher = pattern.matcher( "8520" );
// Perform the match
if (matcher.find()) {
System.out.println( "Match found: " + matcher.group());
}
// Reset the Pattern for a different string
matcher.reset( "kkhgt5678" );
System.out.println( "After resetting the Matcher " );
// Perform the match again
if (matcher.find()) {
System.out.println( "Match found: " + matcher.group());
}
}
} |
Match found: 8520 After resetting the Matcher Match found: 5678
Explaination of the above Program:
- Create a Pattern Object
- Use the Matcher to Match against a String
- Reset the Pattern for a Different String
This demonstrates the successful reset of the Pattern for a different input string.