How to create a split screen display with one frame and canvas

I am creating a 2D Java game, which looks like this:

My question is what should I do to my display to create two 'separate' displays. I plan on doubling the height of the program, and have a second display which is able to render completely separately to the top display. I'd like it to look like this:

I would like to not have to click between the two displays to be able for them to recognize input. I think this could be done by just keeping one canvas and just commanding the canvas to draw in certain areas? I also am not planning on using any external libraries.

Game class: (Some irrelevant code removed)

public class Game implements Runnable {

private Display display;
private int width, height;
public String title;

private Thread thread;
private boolean running = false;

private BufferStrategy bs;
private Graphics g;

public State gameState;
public State menuState;

private Handler handler;

public Game(String title, int width, int height) {
    this.width = width;
    this.height = height;
    this.title = title;
}

private void tick() {
    // Ticks the current game state
    if(StateManager.getState() != null) {
        StateManager.getState().tick();
    }
}

private void render() {
    bs = display.getCanvas().getBufferStrategy();
    if(bs == null) {
        display.getCanvas().createBufferStrategy(3);
        return;
    }
    g = bs.getDrawGraphics();

    //Clear screen
    g.clearRect(0, 0, width, height);

    // Gets the current game state and runs its render method
    if(StateManager.getState() != null) {
        StateManager.getState().render(g);
    }

    // End drawing
    bs.show();
    g.dispose();
}

// Initialize the display, assets, and game states
public void init() {
    display = new Display(title, width, height);
    display.getFrame().addKeyListener(keyManager);
    display.getFrame().addMouseListener(mouseManager);
    display.getFrame().addMouseMotionListener(mouseManager);
    display.getCanvas().addMouseListener(mouseManager);
    display.getCanvas().addMouseMotionListener(mouseManager);

    Assets.init();

    handler = new Handler(this);

    gameState = new GameState(handler);
    menuState = new MenuState(handler);

    StateManager.setState(gameState);
}

public void run() {
    init();

    // Some unimportant code is removed for sake of space
    while (running) {
        tick();
        render();
    }

    stop();
}

}

Display class:

public class Display {

private JFrame frame;
private Canvas canvas;

private String title;
private int width, height;

public Display(String title, int width, int height) {
    this.title = title;
    this.width = width;
    this.height = height;

    createDisplay();
}

private void createDisplay() {
    frame = new JFrame(title);
    frame.setSize(width, height);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setResizable(false);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);

    canvas = new Canvas();
    canvas.setPreferredSize(new Dimension(width, height));
    canvas.setMaximumSize(new Dimension(width, height));
    canvas.setMinimumSize(new Dimension(width, height));
    canvas.setFocusable(false);

    frame.add(canvas);
    frame.pack();
}

public Canvas getCanvas() {
    return canvas;
}

public JFrame getFrame() {
    return frame;
}

}

Launcher class:

public class Launcher {

private final static String TITLE = "Game";
private final static int WIDTH = 256;
private final static int HEIGHT = 192;

public static void main(String[] args) {
    Game game = new Game(TITLE, WIDTH, HEIGHT);
    game.start();
}

}