NB4L1

import java.awt.*;import java.awt.event.*;import java.util.Random;import java.util.Vector;class Simulator extends Frame implements ActionListener{	public static void main(String[] args)	{		new Simulator("Simulator");	}		public static final int MAX_X = 700;	public static final int MAX_Y = 700;	public static final int	START_RADIUS = 200;	public static final int	START_COUNT = 10;	public static final int	ATOM_RADIUS = 2;	public static final int	ATOM_DIAMETER = 2 * ATOM_RADIUS;	public static final double SPEED_LOSS = -0.95;	public static final double PERIOD_TIME = 0.001 * 2;	public static final double START_GRAV_MULTI = 1;		Vector<Atom> _atoms;	Image _back;	Graphics _gc;	DrawArea _area;	Gravity _grav;	TextField _tf, _tf2;		boolean _path = false;		Simulator(String s)	{		super(s);				setVisible(true);		setResizable(false);				addWindowListener(new MyWindowAdapter());				// ===				Button restart = new Button("Restart");		Button path = new Button("Path");				restart.addActionListener(this);		path.addActionListener(this);				Panel north = new Panel();		north.setLayout(new FlowLayout());		north.add(restart);		north.add(path);				add("North", north);				// ===				_area = new DrawArea();		_area.addMouseListener(new MyMouseAdapter());				add("Center", _area);				// ===				_tf = new TextField("0%",3);		_tf2 = new TextField("0%",3);				Panel south = new Panel();		south.setLayout(new FlowLayout());		south.add(new Label("Gravity"));		south.add(new Label("x:"));		south.add(_tf);		south.add(new Label("y:"));		south.add(_tf2);				add("South", south);				// ===				_grav = new Gravity();				setText();		pack();	}		void setText()	{		int xx = (int)(200 * _grav._vx / _area.getWidth());		int yy = (int)(200 * _grav._vy / _area.getHeight());				_tf.setText(String.valueOf(xx) + "%");		_tf2.setText(String.valueOf(yy) + "%");	}		class MyMouseAdapter extends MouseAdapter	{		public void mousePressed(MouseEvent e)		{			int x = e.getX(); 			int y = e.getY();						_grav._vx = x - _area.getCenterX();			_grav._vy = y - _area.getCenterY();						setText();		}	}		public void actionPerformed(ActionEvent e)	{		if (e.getActionCommand().equals("Restart"))		{			_grav.init();		}		else if (e.getActionCommand().equals("Path"))		{			_path = !_path;			_area.clean();		}	}		class MyWindowAdapter extends WindowAdapter	{		public void windowClosing(WindowEvent event)		{			System.exit(0);		}	}		class DrawArea extends Canvas	{		int _centerX, _centerY;				DrawArea()		{			setSize(MAX_X, MAX_Y);			_centerX = getWidth() / 2;			_centerY = getHeight() / 2;						initBuffer();		}				void initBuffer()		{			_back = Simulator.this.createImage(MAX_X, MAX_Y);						Graphics gc = _back.getGraphics();						gc.setColor(Color.lightGray);			gc.fillRect(0, 0, getWidth(), getHeight());			_gc = gc;		}				void draw()		{			getGraphics().drawImage(_back, 0, 0, this);		}				void clear()		{			_gc.setColor(Color.lightGray);			_gc.fillRect(0, 0, getWidth(), getHeight());		}				void clean()		{			initBuffer();		}				void paint()		{			for (Atom a : _atoms)			{				_gc.setColor(a._color);				_gc.fillOval(a.getDrawX(), a.getDrawY(), ATOM_DIAMETER, ATOM_DIAMETER);			}						_gc.setColor(Color.black);			_gc.drawLine((int)(_area.getCenterX() + _grav._vx), (int)(_area.getCenterY() + _grav._vy), _area.getCenterX(), _area.getCenterY());						_gc.setColor(Color.white);			_gc.fillOval(_area.getCenterX() - ATOM_RADIUS, _area.getCenterY() - ATOM_RADIUS, 6, 6);						_gc.setColor(Color.black);			_gc.drawOval(_area.getCenterX() - ATOM_RADIUS, _area.getCenterY() - ATOM_RADIUS, 6, 6);						_gc.drawRect(0, 0, _area.getWidth() - 1, _area.getHeight() - 1);		}				int getCenterX()		{			return _centerX;		}				int getCenterY()		{			return _centerY;		}	}		class Gravity extends Thread	{		double _vx, _vy;				Gravity()		{			init();			start();		}				void init()		{			_atoms = new Vector<Atom>();						for (int i = 0; i < START_COUNT; i++)			{				_atoms.add(new Atom());			}						_vx = 0;			_vy = (double)_area.getCenterY() * START_GRAV_MULTI;						_area.clean();		}				public void run()		{			int count = 0;						long _update = 0;			int _count = 0;			for(;;)			{				if (_update + 1000 < System.currentTimeMillis())				{					System.out.println(_count + 1);					_update = System.currentTimeMillis();					_count = 0;				}				else				{					_count++;				}								try				{					if (!_path)						_area.clear();				} catch (Exception e) { }								try				{					moveAtoms();				} catch (Exception e) { }								try				{					_area.paint();				} catch (Exception e) { }								if (count == 20)				{					_area.draw();					count = 0;				}				else				{					count++;				}								waiter(1);			}		}				long _lastCall = System.currentTimeMillis();				void waiter(long time)		{			while(_lastCall > System.currentTimeMillis())			{				try				{					sleep(0,1);				} catch (Exception e) { }			}						_lastCall += time;		}				void moveAtoms()		{			for(Atom a : _atoms)			{				a.move();			}		}	}		/*static Color[] _colors = {		Color.BLACK,		Color.BLUE,		Color.CYAN,		Color.DARK_GRAY,		//Color.GRAY,		Color.GREEN,		Color.LIGHT_GRAY,		Color.MAGENTA,		Color.ORANGE,		Color.PINK,		Color.RED,		Color.WHITE,		Color.YELLOW,	};*/		class Atom	{		double _x, _y, _vx, _vy;		Color _color;				Atom()		{			int x = 0;			int y = 0;			for(;;)			{				x = (int)((Math.random() * 2 - 1) * 200);				y = (int)((Math.random() * 2 - 1) * 200);								if (x * x + y * y < START_RADIUS * START_RADIUS)					break;			}						_x = _area.getCenterX() + x;			_y = _area.getCenterY() + y;			_vx = x;			_vy = y;						//_color = _colors[new Random().nextInt(_colors.length)];			_color = new Color((int)(Math.random()*256),(int)(Math.random()*256),(int)(Math.random()*256));		}				int getDrawX()		{			return (int)_x - ATOM_RADIUS;		}				int getDrawY()		{			return (int)_y - ATOM_RADIUS;		}				void move()		{			int x = (int)_x;			int y = (int)_y;						if ((x <= ATOM_RADIUS && _vx < 0) || (_area.getWidth() - x <= ATOM_RADIUS && 0 < _vx))				_vx *= SPEED_LOSS;						if ((y <= ATOM_RADIUS && _vy < 0) || (_area.getHeight() - y <= ATOM_RADIUS && 0 < _vy))				_vy *= SPEED_LOSS;						_x += _vx * PERIOD_TIME;			_y += _vy * PERIOD_TIME;						_vx += _grav._vx * PERIOD_TIME;			_vy += _grav._vy * PERIOD_TIME;		}	}}