The following should work:
public static void main(String[] args)
{
final String title = "Test Window";
final int width = 1200;
final int height = width / 16 * 9;
//Creating the frame.
JFrame frame = new JFrame(title);
frame.setSize(width, height);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setResizable(false);
frame.setVisible(true);
//Creating the canvas.
Canvas canvas = new Canvas();
canvas.setSize(width, height);
canvas.setBackground(Color.BLACK);
canvas.setVisible(true);
canvas.setFocusable(false);
//Putting it all together.
frame.add(canvas);
canvas.createBufferStrategy(3);
boolean running = true;
BufferStrategy bufferStrategy;
Graphics graphics;
while (running) {
bufferStrategy = canvas.getBufferStrategy();
graphics = bufferStrategy.getDrawGraphics();
graphics.clearRect(0, 0, width, height);
graphics.setColor(Color.GREEN);
graphics.drawString("This is some text placed in the top left corner.", 5, 15);
bufferStrategy.show();
graphics.dispose();
}
}