To match HTML tags using Java regular expressions, you can use the following approach:

1. Import the necessary classes:

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

2. Define a regular expression pattern to match the desired HTML tag pattern. For example, to match all <a> tags with an href attribute, you can use the following pattern:

   String pattern = "<a\\s+[^>]*\\bhref\\b\\s*=\\s*\"([^\"]*)\"[^>]*>";
   

In this pattern:

• \\s+ matches one or more whitespace characters.
• [^>]* matches any character except > zero or more times.
• \\bhref\\b matches the word “href” as a whole word.
• \\s*=\\s*\"([^\"]*)\" matches an attribute with its value (enclosed in double quotes).

1. Create a Pattern object using the pattern string:

   Pattern tagPattern = Pattern.compile(pattern);
   

2. Create a Matcher object to perform matching on the input HTML document:

   Matcher matcher = tagPattern.matcher(htmlContent);
   

3. Iterate through the matches and extract the desired information. For example, to extract the URLs from the matched <a> tags:

   while (matcher.find()) {
    String href = matcher.group(1);
    System.out.println(href);
   }
   

In the above code, matcher.group(1) retrieves the content of the first capturing group, which corresponds to the captured URL.

Note: While using regular expressions to parse HTML can be effective for simple cases, it is generally recommended to use a dedicated HTML parser library like JSoup for more complex HTML parsing tasks.

#Java #RegularExpressions