With this example we are going to demonstrate how to use Matcher.lookingAt() API method to match an input sequence, starting at the beginning of the input, against a specified pattern. In short, to match a Sting input against a pattern with Matcher.lookingAt() API method you should:
- Compile a String regular expression to a Pattern, using
compile(String regex)API method of Pattern. - Use
matcher(CharSequence input)API method of Pattern to create a Matcher that will match the given String input against this pattern. - Use
lookingAt()API method of Matcher to match the input against the pattern, starting from the beginning of the input, but without requiring that the entire region be matched. - Reset the matcher with a new input sequence with
reset(CharSequence input)API method to match a new String input against the pattern.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class MatcherLookingAt {
public static void main(String args[]) {
Pattern pattern = Pattern.compile("J2SE");
String str1 = "J2SE is the only one for me";
String str2 = "For me, it's J2SE, or nothing at all";
String str3 = "J2SEistheonlyoneforme";
Matcher m = pattern.matcher(str1);
String msg = ":" + str1 + ": matches?: ";
System.out.println(msg + m.lookingAt());
m.reset(str2);
msg = ":" + str2 + ": matches?: ";
System.out.println(msg + m.lookingAt());
m.reset(str3);
msg = ":" + str3 + ": matches?: ";
System.out.println(msg + m.lookingAt());
}
}
Output:
:J2SE is the only one for me: matches?: true
:For me, it's J2SE, or nothing at all: matches?: false
:J2SEistheonlyoneforme: matches?: true
This was an example of Matcher.lookingAt() API method in Java.
