Read regular expression from console : Introduction « Regular Expressions « Java Tutorial






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import java.io.Console;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

public class RegexTestHarness2 {

  public static void main(String[] args) {
    Pattern pattern = null;
    Matcher matcher = null;

    Console console = System.console();
    if (console == null) {
      System.err.println("No console.");
      System.exit(1);
    }
    while (true) {
      try {
        pattern = Pattern.compile(console.readLine("%nEnter your regex: "));

        matcher = pattern.matcher(console
            .readLine("Enter input string to search: "));
      } catch (PatternSyntaxException pse) {
        console.format("There is a problem with the regular expression!%n");
        console.format("The pattern in question is: %s%n", pse.getPattern());
        console.format("The description is: %s%n", pse.getDescription());
        console.format("The message is: %s%n", pse.getMessage());
        console.format("The index is: %s%n", pse.getIndex());
        System.exit(0);
      }
      boolean found = false;
      while (matcher.find()) {
        console.format("I found the text \"%s\" starting at "
            + "index %d and ending at index %d.%n", matcher.group(), matcher
            .start(), matcher.end());
        found = true;
      }
      if (!found) {
        console.format("No match found.%n");
      }
    }
  }
}








8.1.Introduction
8.1.1.Meta-characters predefined to match specific characters.
8.1.2.Meta-characters to match against certain string boundaries.
8.1.3.Regular expression languages also have character classes.
8.1.4.POSIX character classes and Java character classes
8.1.5.Java Character Class
8.1.6.Match a particular character a specified number of times.
8.1.7.Read regular expression from console
8.1.8.Regex Test Harness
8.1.9.Match Java source file and file and class name
8.1.10.Finding all words that start with an 'a'
8.1.11.Simple validation using the Pattern and Matcher objects
8.1.12.A possessive qualifier
8.1.13.Find the starting point of the second 'Bond'
8.1.14.A negative look ahead
8.1.15.A negative behind ahead
8.1.16.A positive look ahead
8.1.17.Pattern helper
8.1.18.Escapes characters that have special meaning to regular expressions