problem with loop message is sent continually

//GUI CLIENT
 
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
 
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
 
public class GUIClient extends JFrame  {
 
	private static final long serialVersionUID = -3054541431624115776L;
 
	private Socket clientSocket;
 
	static MyEnhancedBoard myBoard;
 
	public Container contentPane;
 
	//static LODServer server=null;
 
	static LODServer s;
	//int port;
	//int players;
	//static String  map;
 
	public GUIClient(LODServer s) throws UnknownHostException, IOException {
		//s= server;
 
		//	s.setup(port,players, map);
 
 
//		PrintMap(s);
 
		setTitle("Labyrinth");
		setSize(1000,1000);
		setDefaultCloseOperation(EXIT_ON_CLOSE);
 
		//getContentPane().add(jsp);
 
 
 
		setVisible(true);	
 
 
		//Client part:
 
		String hostname = "localhost"; 
		int portNumber = 4455;
 
		clientSocket = new Socket(hostname, portNumber);
 
 
 
		System.out.println("Connection establised");
 
//		setSize(900,800); // Any size, reset it later.
 
		contentPane = getContentPane();
		contentPane.setLayout(new BorderLayout());
 
 
//		640*480:
		//myBoard = new MyEnhancedBoard("Blank.jpg",0,0,8,10,64,60);
 
 
		myBoard = new MyEnhancedBoard("Images/Blank.jpg",20,20,s.mapWidth,s.mapHeight, 40,40);
 
		//myBoard = new MyEnhancedBoard("Images/Blank.jpg",20,20,s.mapWidth,s.mapHeight, 40,40);
 
//		myBoard = new MyEnhancedBoard("Blank.jpg",20,20,s.mapWidth,s.mapHeight, 60,60);
 
 
 
 
 
		System.out.println("");
 
		myBoard.setNoOfTiles(10000); // Total number of tiles
//		setTile(int tileId, int boardCoordX,int boardCoordY,String iconName)
 
 
 
		/*
		//According to the given NUMBER OF PLAYERS CREATE THE SAME Number OF CLIENTS:
		int id=200;
		for (int i=1; i<= s.clients.size(); i++)
		{
			//new Client();
			myBoard.setTile(id++,2,2,"Images/Cool1.jpg"); 
		}
		 */
 
 
//		SG_Board smallMap.add(myBoard = new MyEnhancedBoard("Blank.jpg",10,5,s.mapWidth,s.mapHeight, 40,40));
 
 
		contentPane = getContentPane();
		contentPane.setLayout(new BorderLayout());
 
 
		JPanel smallMap = new JPanel();
 
		myBoard.add(smallMap, BorderLayout.WEST);  
 
 
		JScrollPane jsp = new JScrollPane(myBoard);
		contentPane.add("Center", jsp);
 
 
//		contentPane.add();
		JButton goUpButton = new JButton("Up");
		JButton goDownButton = new JButton("Down");
		JButton goLeftButton = new JButton("Left");
		JButton goRightButton = new JButton("Right");
 
		goUpButton.addActionListener(myBoard);
		goDownButton.addActionListener(myBoard);
		goLeftButton.addActionListener(myBoard);
		goRightButton.addActionListener(myBoard);
		contentPane.add("West",goLeftButton);
		contentPane.add("East",goRightButton);
		contentPane.add("North",goUpButton);
		contentPane.add("South", goDownButton);
 
		setVisible(true);
 
 
 
//		for (int i=1; i<= s.clients.size(); i++)
//		{
//		new Client();
 
		myBoard.setTile(1,2,2,"Images/Cool1.jpg"); 
		SG_Board.setCurrentTileID(1);
//		new Inventory();
 
 
 
 
		int idmap = 2;
		for(int a=0;a<s.mapHeight;a++)
		{
			for(int b=0;b<s.mapWidth;b++)
			{
				switch(s.map[a][b])
				{					
 
					/*tileId,x,y, ImageFile*/
 
					case LODServer.EMPTY :   myBoard.setTile(++idmap,b,a,"Images/floor.jpg"); break;
					case LODServer.HEALTH :  myBoard.setTile(++idmap,b,a,"Images/health.jpg"); break;
					case LODServer.LANTERN : myBoard.setTile(++idmap,b,a,"Images/lantern.jpg"); break;
					case LODServer.SWORD :   myBoard.setTile(++idmap,b,a,"Images/sword.jpg"); break;
					case LODServer.ARMOUR :  myBoard.setTile(++idmap,b,a,"Images/armour.jpg"); break;
					case LODServer.EXIT :    myBoard.setTile(++idmap,b,a,"Images/exit.jpg"); 
					SG_Board.INERT_TILE_ID = idmap;
					break;
					case LODServer.WALL :    myBoard.setTile(++idmap,b,a,"Images/wall.jpg"); break;
					case LODServer.TREASURE : myBoard.setTile(++idmap,b,a,"Images/gold.jpg"); break;
				}
				if(s.map[a][b] > 0)
				{
					myBoard.setTile(++idmap,b,a,"Images/floor.jpg"); break;
				}
 
			}
			repaint();
		}
//		}
		repaint();
 
 
 
 
//		menu code:
		JMenuBar menuBar = new JMenuBar();
 
		setJMenuBar(menuBar);
 
		JMenu fileMenu = new JMenu("File");
		JMenu sendCommand = new JMenu("Command");
 
		menuBar.add(fileMenu);
		menuBar.add(sendCommand);
 
		JMenuItem openAction = new JMenuItem("Load new map");
		JMenuItem exitAction = new JMenuItem("Exit");
 
		JMenuItem sendcmd = new JMenuItem("Send command");
 
 
		sendCommand.add(sendcmd);
 
		fileMenu.add(openAction);
		fileMenu.addSeparator();
		fileMenu.add(exitAction);
 
 
		openAction.setActionCommand("open");  
 
		openAction.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				//openFile();
			}});
 
 
 
 
		exitAction.setActionCommand("exit");   
 
		exitAction.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				System.exit(0);
			}});
 
 
		sendcmd.setActionCommand("sendcmd");
 
		final String sentence = "";
 
		sendcmd.addActionListener(new DialogSender());
 
 
		myBoard.resize(1000,1000);
		myBoard.show();
 
	}//end of constructor
 
 
 
	public File openFile(LODServer s) throws FileNotFoundException	{
		JFileChooser fc = new JFileChooser();
		int res = fc.showOpenDialog(this);
		if(res == JFileChooser.CANCEL_OPTION)
			return null;
 
		File file = fc.getSelectedFile();
		if(!file.exists())
			return null;
		//server.loadMap(file.getAbsolutePath());
		s.loadMap(file.getAbsolutePath());
 
		return file;
 
	}
	public static void main(String[] args) throws UnknownHostException, IOException {
		if (GUIClient.s == null) {
			new GUIClient(new LODServer());
		}
		else {
			new GUIClient(GUIClient.s); // You would be better with an empty constructor
		}
	}
 
	class DialogSender implements ActionListener {
		public void actionPerformed(ActionEvent ae) {
			PrintWriter outToServer = null; 
			try {
				outToServer = new PrintWriter(new OutputStreamWriter(
						clientSocket.getOutputStream()));
 
				String sentence = JOptionPane.showInputDialog("Send a command:");
 
 
				while ((sentence.trim()) != null){
					/* send the sentence to the server */
					outToServer.println(sentence);
				}
				outToServer.flush();
 
			} catch (IOException e) {
				e.printStackTrace();
			} finally {
				try {
					outToServer.close();
				} catch (Exception e) { /* ignore */
				}
			}
		}
 
 
	}
 
 
}