Added documentation, refined exception handling

src/main/java/envoy/client/Client.java

@@ -33,8 +33,23 @@ public class Client {
 	private User			sender, recipient;
 	private boolean			online			= false;
 
+	/**
+	 * Initializes the client. At this state, the client user has yet to be
+	 * initialized, which can be done by calling {@link Client#onlineInit(String).
+	 * 
+	 * @param config The {@link Config} instance to use in this client
+	 * @since Envoy v0.2-alpha
+	 */
 	public Client(Config config) { this.config = config; }
 
+	/**
+	 * Enters the online mode by acquiring a user ID from the server.
+	 * 
+	 * @param userName the name of the client user
+	 * @throws EnvoyException if the online mode could not be entered or the request
+	 *                        failed for some other reason
+	 * @since Envoy v0.2-alpha
+	 */
 	public void onlineInit(String userName) throws EnvoyException {
 		sender	= getUser(userName);
 		online	= true;
@@ -52,10 +67,8 @@ public class Client {
 	}
 
 	/**
-	 * Returns a {@code Map<String, User>} of all users on the server with their
+	 * @return a {@code Map<String, User>} of all users on the server with their
-	 * user names as keys.
+	 *         user names as keys
-	 * 
-	 * @return Sync - List of all users on the server.
 	 * @since Envoy v0.2-alpha
 	 */
 	public Map<String, User> getUsers() {
@@ -138,9 +151,12 @@ public class Client {
 	 * @param sync   the sync object (yet to be converted from java class to
 	 *               sync.xml)
 	 * @return a returnSync.xml file
+	 * @throws EnvoyException if the client is not in online mode
 	 * @since Envoy v0.1-alpha
 	 */
-	public Sync sendSync(long userId, Sync sync) {
+	public Sync sendSync(long userId, Sync sync) throws EnvoyException {
+		if(!isOnline())
+			throw new EnvoyException("Client is not in online mode");
 		// Print sync XML to console
 		JAXBContext jc;
 		try {
@@ -162,6 +178,12 @@ public class Client {
 	 */
 	public User getSender() { return sender; }
 
+	/**
+	 * Sets the client user which is used to send messages.
+	 * 
+	 * @param sender the client user to set
+	 * @since Envoy v0.2-alpha
+	 */
 	public void setSender(User sender) { this.sender = sender; }
 
 	/**
@@ -173,7 +195,7 @@ public class Client {
 	/**
 	 * Sets the recipient.
 	 * 
-	 * @param recipient - the recipient to set
+	 * @param recipient the recipient to set
 	 * @since Envoy v0.1-alpha
 	 */
 	public void setRecipient(User recipient) { this.recipient = recipient; }
@@ -186,6 +208,7 @@ public class Client {
 
 	/**
 	 * @return {@code true} if a connection to the server could be established
+	 * @since Envoy v0.2-alpha
 	 */
 	public boolean isOnline() { return online; }
 }

src/main/java/envoy/client/LocalDB.java

@@ -54,6 +54,7 @@ public class LocalDB {
 	 * Constructs an empty local database. To serialize any chats to the file
 	 * system, call {@link LocalDB#initializeDBFile(File)}.
 	 *
+	 * @param localDBDir the directory in which to store users and chats
 	 * @since Envoy v0.1-alpha
 	 */
 	public LocalDB(File localDBDir) throws IOException {
@@ -72,20 +73,19 @@ public class LocalDB {
 	}
 
 	/**
-	 * Initializes the local database and fills it with values
+	 * Creates a database file for a user-specific list of chats.
-	 * if the user has already sent or received messages.
 	 *
-	 * @param localDBDir the directory where we wish to save/load the database from.
+	 * @throws NullPointerException if the client user is not yet specified
-	 * @throws EnvoyException if the directory selected is not an actual directory.
 	 * @since Envoy v0.1-alpha
 	 */
-	public void initializeDBFile() throws EnvoyException {
+	public void initializeDBFile() {
 		if (user == null) throw new NullPointerException("Client user is null");
 		localDBFile = new File(localDBDir, user.getID() + ".db");
 	}
 
 	/**
-	 * Saves the database into a file for future use.
+	 * Stores all users to the local database. If the client user is specified, the
+	 * chats related to this user are stored as well.
 	 *
 	 * @throws IOException if something went wrong during saving
 	 * @since Envoy v0.1-alpha
@@ -98,30 +98,36 @@ public class LocalDB {
 		write(localDBFile, chats);
 	}
 
+	/**
+	 * Loads all users that are stored in the local database.
+	 * 
+	 * @throws EnvoyException if the loading process failed
+	 * @since Envoy v0.2-alpha
+	 */
 	@SuppressWarnings("unchecked")
-	public void loadUsers() throws ClassNotFoundException, IOException { users = read(usersFile, HashMap.class); }
+	public void loadUsers() throws EnvoyException { users = read(usersFile, HashMap.class); }
 
 	/**
 	 * Loads all chats saved by Envoy for the client user.
 	 *
-	 * @throws EnvoyException         if something fails while loading.
+	 * @throws EnvoyException if the loading process failed
-	 * @throws IOException
-	 * @throws ClassNotFoundException
 	 * @since Envoy v0.1-alpha
 	 */
 	@SuppressWarnings("unchecked")
-	public void loadChats() throws ClassNotFoundException, IOException { chats = read(localDBFile, ArrayList.class); }
+	public void loadChats() throws EnvoyException { chats = read(localDBFile, ArrayList.class); }
 
-	private <T> T read(File file, Class<T> serializedClass) throws ClassNotFoundException, IOException {
+	private <T> T read(File file, Class<T> serializedClass) throws EnvoyException {
+		if (file == null) throw new NullPointerException("File is null");
 		try (ObjectInputStream in = new ObjectInputStream(new FileInputStream(file))) {
 			return serializedClass.cast(in.readObject());
 		} catch (ClassNotFoundException | IOException e) {
-			throw e;
+			throw new EnvoyException("Could not load serialized object", e);
 		}
 	}
 
 	private <T> void write(File file, T obj) throws IOException {
 		if (file == null) throw new NullPointerException("File is null");
+		if (obj == null) throw new NullPointerException("Object to serialize is null");
 		if (!file.exists()) {
 			file.getParentFile().mkdirs();
 			file.createNewFile();
@@ -306,7 +312,8 @@ public class LocalDB {
 	public void clearUnreadMessagesSync() { unreadMessagesSync.getMessages().clear(); }
 
 	/**
-	 * @return the users
+	 * @return a {@code Map<String, User>} of all users stored locally with their user names as keys
+	 * @since Envoy v0.2-alpha
 	 */
 	public Map<String, User> getUsers() { return users; }
 

src/main/java/envoy/client/ui/ChatWindow.java

@@ -239,8 +239,7 @@ public class ChatWindow extends JFrame {
 
 		loadUsersAndChats();
 
-		if(client.isOnline())
+		if (client.isOnline()) startSyncThread(Config.getInstance().getSyncTimeout());
-			startSyncThread(Config.getInstance().getSyncTimeout());
 
 		contentPane.revalidate();
 	}
@@ -342,7 +341,11 @@ public class ChatWindow extends JFrame {
 			new Thread(() -> {
 
 				// Synchronize
+				try {
 					localDB.applySync(client.sendSync(client.getSender().getID(), localDB.fillSync(client.getSender().getID())));
+				} catch (Exception e) {
+					logger.log(Level.SEVERE, "Could not perform sync", e);
+				}
 
 				// Process unread messages
 				localDB.addUnreadMessagesToLocalDB();

src/main/java/envoy/client/ui/Startup.java

@@ -97,7 +97,7 @@ public class Startup {
 		try {
 			localDB.initializeDBFile();
 			localDB.loadChats();
-		} catch (EnvoyException | ClassNotFoundException | IOException e) {
+		} catch (EnvoyException e) {
 			e.printStackTrace();
 			JOptionPane.showMessageDialog(null,
 					"Error while loading local database: " + e.toString() + "\nChats will not be stored locally.",