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About Ilias Tsagklis

Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Matcher lookingAt example

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.

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