Added ChatSynchronizer class to store chats locally

.gitignore

@@ -1 +1,2 @@
 /target/
+/local_chats.db

src/main/java/envoy/client/Chat.java

@@ -1,11 +1,15 @@
 package envoy.client;
 
+import java.io.Serializable;
+
 import javax.swing.DefaultListModel;
 
 import envoy.schema.Message;
 import envoy.schema.User;
 
-public class Chat {
+public class Chat implements Serializable {
+
+	private static final long serialVersionUID = -7751248474547242056L;
 	
 	private User						recipient;
 	private DefaultListModel<Message>	model	= new DefaultListModel<>();

src/main/java/envoy/client/ChatSynchronizer.java

@@ -0,0 +1,47 @@
+package envoy.client;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>ChatSynchronizer.java</strong><br>
+ * Created: <strong>27.10.2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy v0.1-alpha
+ */
+public class ChatSynchronizer {
+
+	private File		localDB;
+	private List<Chat>	chats	= new ArrayList<>();
+
+	public ChatSynchronizer(String localDBPath) {
+		localDB = new File(localDBPath);
+		if (localDB.exists() && !localDB.isDirectory()) loadFromLocalDB();
+	}
+
+	public void saveToLocalDB() {
+		try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(localDB))) {
+			out.writeObject(chats);
+		} catch(IOException ex) {
+			ex.printStackTrace();
+		}
+	}
+	
+	@SuppressWarnings("unchecked")
+	private void loadFromLocalDB() {
+		try (ObjectInputStream in = new ObjectInputStream(new FileInputStream(localDB))) {
+			Object obj = in.readObject();
+			if (obj instanceof ArrayList<?>) chats = (ArrayList<Chat>) obj;
+		} catch (ClassNotFoundException | IOException e) {}
+	}
+
+	public List<Chat> getChats() { return chats; }
+}

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

@@ -6,8 +6,8 @@ import java.awt.Font;
 import java.awt.GridBagConstraints;
 import java.awt.GridBagLayout;
 import java.awt.Insets;
-import java.util.ArrayList;
-import java.util.List;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
 
 import javax.swing.DefaultListModel;
 import javax.swing.JButton;
@@ -24,6 +24,7 @@ import javax.swing.Timer;
 import javax.swing.border.EmptyBorder;
 
 import envoy.client.Chat;
+import envoy.client.ChatSynchronizer;
 import envoy.client.Client;
 import envoy.schema.Message;
 import envoy.schema.Messages;
@@ -46,20 +47,30 @@ public class ChatWindow extends JFrame {
 
 	private JPanel contentPane = new JPanel();
 
-	private Client client;
+	private Client				client;
+	private ChatSynchronizer	chatSynchronizer;
 
-	private JList<User>	userList		= new JList<>();
-	private List<Chat>	partnerChatList	= new ArrayList<Chat>();
+	private JList<User>	userList	= new JList<>();
 	private Chat		currentChat;
 
-	public ChatWindow(Client client) {
-		this.client = client;
+	public ChatWindow(Client client, ChatSynchronizer chatSynchronizer) {
+		this.client				= client;
+		this.chatSynchronizer	= chatSynchronizer;
 
 		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 		setBounds(100, 100, 600, 800);
 		setTitle("Envoy");
 		setLocationRelativeTo(null);
 
+		// Save chats when window closes
+		addWindowListener(new WindowAdapter() {
+
+			@Override
+			public void windowClosing(WindowEvent e) {
+				chatSynchronizer.saveToLocalDB();
+			}
+		});
+		
 		contentPane.setBackground(new Color(0, 0, 0));
 		contentPane.setForeground(Color.white);
 		contentPane.setBorder(new EmptyBorder(0, 5, 0, 0));
@@ -138,7 +149,8 @@ public class ChatWindow extends JFrame {
 
 		postButton.addActionListener((evt) -> {
 			if (!client.hasRecipient()) {
-				JOptionPane.showMessageDialog(this, "Please select a recipient!", "Cannot send message", JOptionPane.INFORMATION_MESSAGE);
+				JOptionPane.showMessageDialog(this, "Please select a recipient!", "Cannot send message",
+						JOptionPane.INFORMATION_MESSAGE);
 				return;
 			}
 
@@ -158,8 +170,7 @@ public class ChatWindow extends JFrame {
 			} catch (Exception e) {
 				JOptionPane.showMessageDialog(this,
 						"An exception occured while sending a message. See the log for more details.",
-						"Exception occured",
-						JOptionPane.ERROR_MESSAGE);
+						"Exception occured", JOptionPane.ERROR_MESSAGE);
 				e.printStackTrace();
 			}
 		});
@@ -186,12 +197,18 @@ public class ChatWindow extends JFrame {
 		userList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
 		userList.addListSelectionListener((listSelectionEvent) -> {
 			if (!listSelectionEvent.getValueIsAdjusting()) {
-				@SuppressWarnings("unchecked")
+				@SuppressWarnings(
+					"unchecked"
+				)
 				final JList<User>	selectedUserList	= (JList<User>) listSelectionEvent.getSource();
 				final User			user				= selectedUserList.getSelectedValue();
 				client.setRecipient(user);
 
-				currentChat = partnerChatList.stream().filter(chat -> chat.getRecipient().getID() == user.getID()).findFirst().get();
+				currentChat = chatSynchronizer.getChats()
+					.stream()
+					.filter(chat -> chat.getRecipient().getID() == user.getID())
+					.findFirst()
+					.get();
 
 				client.setRecipient(user);
 
@@ -232,7 +249,15 @@ public class ChatWindow extends JFrame {
 		new Thread(() -> {
 			Users					users			= client.getUsersListXml();
 			DefaultListModel<User>	userListModel	= new DefaultListModel<>();
-			users.getUser().forEach(user -> { userListModel.addElement(user); partnerChatList.add(new Chat(user)); });
+			users.getUser().forEach(user -> {
+				userListModel.addElement(user);
+
+				// Check if user exists in local DB
+				if (chatSynchronizer.getChats()
+					.stream()
+					.filter(c -> c.getRecipient().getID() == user.getID())
+					.count() == 0) chatSynchronizer.getChats().add(new Chat(user));
+			});
 			SwingUtilities.invokeLater(() -> userList.setModel(userListModel));
 		}).start();
 	}
@@ -247,9 +272,11 @@ public class ChatWindow extends JFrame {
 		new Timer(timeout, (evt) -> {
 			Messages unreadMessages = client.getUnreadMessages(client.getSender().getID());
 			for (int i = 0; i < unreadMessages.getMessage().size(); i++)
-				for (int j = 0; j < partnerChatList.size(); j++)
-					if (partnerChatList.get(j).getRecipient().getID() == unreadMessages.getMessage().get(i).getMetaData().getSender())
-						partnerChatList.get(j).appendMessage(unreadMessages.getMessage().get(i));
+				for (int j = 0; j < chatSynchronizer.getChats().size(); j++)
+					if (chatSynchronizer.getChats().get(j)
+						.getRecipient()
+						.getID() == unreadMessages.getMessage().get(i).getMetaData().getSender())
+						chatSynchronizer.getChats().get(j).appendMessage(unreadMessages.getMessage().get(i));
 		}).start();
 	}
 }

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

@@ -6,6 +6,7 @@ import java.util.Properties;
 
 import javax.swing.JOptionPane;
 
+import envoy.client.ChatSynchronizer;
 import envoy.client.Client;
 import envoy.client.Config;
 
@@ -51,7 +52,7 @@ public class Startup {
 
 		EventQueue.invokeLater(() -> {
 			try {
-				ChatWindow frame = new ChatWindow(client);
+				ChatWindow frame = new ChatWindow(client, new ChatSynchronizer("local_chats.db"));
 				frame.setVisible(true);
 			} catch (Exception e) {
 				e.printStackTrace();