ido

import java.awt.AWTEvent;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.event.KeyEvent;
import java.awt.image.BufferStrategy;

import javax.swing.JFrame;

public class Example extends JFrame {
    final int FRAME_TIME = 1000 / 60; // ~60fps
    int font_height = 10;
    int width_in_chars = 80;

    int height_in_chars = 40;
    BufferStrategy strategy;
    boolean keys[] = new boolean[65536];
    boolean mouse[] = new boolean[8];
    int mouseX = 0;

    int mouseY = 0;

    public Example() {
        Font font = new Font(Font.MONOSPACED, Font.PLAIN, font_height);
        int win_width = width_in_chars * getFontMetrics(font).charWidth(' ');
        int win_height = height_in_chars * font_height;

        setTitle("Example Project");
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setUndecorated(true);
        setFont(font);
        setSize(win_width, win_height);
        setLocationRelativeTo(null);
        setIgnoreRepaint(true);
        setVisible(true);

        enableEvents(AWTEvent.KEY_EVENT_MASK | AWTEvent.MOUSE_EVENT_MASK
                | AWTEvent.MOUSE_MOTION_EVENT_MASK);
        createBufferStrategy(2);

        strategy = getBufferStrategy();
    }

    void mainLoop() {
        long lastFrame = System.nanoTime();

        while (!keys[KeyEvent.VK_ESCAPE]) {
            drawToBuffer();
            strategy.show();

            do
                try {
                    Thread.sleep(FRAME_TIME / 2);
                } catch (InterruptedException e) { }
            while (System.nanoTime() < lastFrame + FRAME_TIME * 1000000);
            lastFrame = System.nanoTime();
        }
        System.exit(0);
    }

    private void drawToBuffer() {
        Graphics2D buffer = (Graphics2D) strategy.getDrawGraphics();
        buffer.drawLine(0, 0, 100, 100);
        buffer.dispose();
    }

    @Override
    public void processKeyEvent(KeyEvent e) {
        keys[e.getKeyCode()] = e.getID() == KeyEvent.KEY_PRESSED;
    }

    public static void main(String[] args) {
        new Example().mainLoop();
    }
}