ComparatorTerminateException

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.Logger;
import org.apache.logging.log4j.message.Message;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;

/**
 * A simple dummy exception for shutting off comparators
 * @author ME1312
 */
public class ComparatorTerminateException extends NullPointerException {
    /**
     * Throw this to shut off a comparator
     */
    public ComparatorTerminateException() {
        super("This exception was thrown so the comparator will turn off");
        DummyExceptionFilter.getFilter(this);
    }

    /**
     * Filters the Exception message from console
     */
    private static class DummyExceptionFilter implements Filter {
        private static DummyExceptionFilter instance = null;
        private ArrayList<Exception> search = new ArrayList<Exception>();
        private Logger logger;

        protected static DummyExceptionFilter getFilter(Exception e) {
            if (instance == null) instance = new DummyExceptionFilter();
            instance.add(e);
            return instance;
        }

        private DummyExceptionFilter() {
            (logger = (Logger) LogManager.getRootLogger()).addFilter(this);
        }

        private void add(Exception e) {
            search.add(e);
        }

        private void remove(Exception e) {
            search.remove(e);
        }

        @Override
        public Result filter(LogEvent event) {
            Result result = Result.NEUTRAL;
            if (event.getMessage().getFormattedMessage() != null && event.getMessage().getFormattedMessage().length() > 0) {
                List<Exception> search = new ArrayList<Exception>();
                search.addAll(this.search);
                for (Exception e : search) {
                    String error = e.getClass().getCanonicalName();
                    if (e.getMessage() != null && e.getMessage().length() > 0) error += ": " + e.getMessage();

                    if (result != Result.DENY && !Pattern.compile(".*" + Pattern.quote(error) + ".*").matcher(event.getMessage().getFormattedMessage()).find()) {
                        this.search.remove(e);
                        result = Result.DENY;
                    }
                }
            }
            return result;
        }

        @Override
        public Result getOnMismatch() {
            return Result.NEUTRAL;
        }

        @Override
        public Result getOnMatch() {
            return Result.NEUTRAL;
        }

        @Override
        public Result filter(Logger logger, Level level, Marker marker, String s, Object... objects) {
            return Result.NEUTRAL;
        }

        @Override
        public Result filter(Logger logger, Level level, Marker marker, Object o, Throwable throwable) {
            return Result.NEUTRAL;
        }

        @Override
        public Result filter(Logger logger, Level level, Marker marker, Message message, Throwable throwable) {
            return Result.NEUTRAL;
        }
    }
}