Problm with tiledlayer object not showing on screen!! plz help

Question

im making a small chess game my chess board is made of Tiledlayer and my chess elements are also Tiledlayer wheneever a move is made i have to make changes to my chess elements cells. but i make changes and they appear on my tiledlayer object but dont show on screen...
when during game when i press FIRE_KEY first time my code goes to a thread and starts a rectangle which blinks and when i press fire again the tiled_layer is updated such that my chess element is moved from selected position to desired position.... but i dont c the change on screen....
here is the complete code of chess board class...
* @(#)ChessCanvas.java
* @author Aaqib
* @version 1.00 1007/9/19
import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
public class ChessCanvas extends GameCanvas implements Runnable{
     private  final int SCREEN_X = getWidth();
     private  final int SCREEN_Y = getHeight();
     private int boardSize = 128;
     // starting point of our chess game
     private int startX = (SCREEN_X - boardSize)/2;
     private int startY = (SCREEN_Y - boardSize)/2;
     // create bounding rectangle to know the end of chess board;
     private int endX = startX + boardSize;
     private int endY = startY + boardSize;
     private static final byte BOARD_COLUMN = 8;
     private static final byte BOARD_ROWS = 8;
     private static final byte TILE_DIMENSION = 16;
     // current X, Y position of cursor
     private byte currentCursorRow;
     private byte currentCursorColumn;
     // the row column which r selected
     private byte selectedRow;
     private byte selectedColumn;
     // the current pixel lcoations
     private int currentPixelX;
     private int currentPixelY;     
     // check if selected. convert curser to red
     private boolean selected = false;
     // background color
     private int white = 0xFCFCFC;
     // the chess board tiled Layer
     private TiledLayer tiledLayer;
     // the chess elements
     private TiledLayer chessElements;
     // layer Manager to add tiles and sprites;
     private LayerManager layerManager;
     // the cursor which selects and moves the objects
     private Sprite cursor;
     // matrix representing the chess board;
     private final byte chkBoard[][] ={
                                   {2,1,2,1,2,1,2,1},
                                   {1,2,1,2,1,2,1,2},
                                   {2,1,2,1,2,1,2,1},
                                   {1,2,1,2,1,2,1,2},
                                   {2,1,2,1,2,1,2,1},
                                   {1,2,1,2,1,2,1,2},
                                   {2,1,2,1,2,1,2,1},
                                   {1,2,1,2,1,2,1,2},
     private final byte elements[][] = {
                                          {6,2,5,4,3,5,2,6},
                                          {1,1,1,1,1,1,1,1},
                                          {0,0,0,0,0,0,0,0},
                                          {0,0,0,0,0,0,0,0},     
                                          {0,0,0,0,0,0,0,0},
                                          {0,0,0,0,0,0,0,0},
                                          {7,7,7,7,7,7,7,7},
                                          {12,8,11,10,9,11,8,12}          
     private Graphics g;
     // main constructor
    public ChessCanvas() {
         super(true);
              setFullScreenMode(true);
              init();
     * Initialize all GUI components
    public void init(){
      try{
             Image spriteImg = Image.createImage("/cursor.png");
             cursor = new Sprite(spriteImg,15,15);
             cursor.setRefPixelPosition(startX - TILE_DIMENSION, startY - TILE_DIMENSION);
            Image img = Image.createImage("/board.png");
            Image elmt = Image.createImage("/chess.png");
            tiledLayer = new TiledLayer(BOARD_COLUMN, BOARD_ROWS, img, TILE_DIMENSION, TILE_DIMENSION);
            chessElements = new TiledLayer(BOARD_COLUMN, BOARD_ROWS, elmt,16,16);
            layerManager = new LayerManager();           
            currentCursorRow = 5;
            currentCursorColumn = 6;
            for (int y = 0; y < BOARD_COLUMN; y++){
                 for (int x = 0; x < BOARD_ROWS; x++){
                      int grid = chkBoard[y][x];
                      int data = elements[y][x];
                      tiledLayer.setCell(x,y, grid);
                      chessElements.setCell(x,y,data);
            g = getGraphics();
            // sets the position of chess board in center
            tiledLayer.move(startX, startY);
            chessElements.move(startX,startY);
            layerManager.append(cursor);
            layerManager.append(chessElements);
            layerManager.append(tiledLayer);
            moveCursor(currentCursorColumn * TILE_DIMENSION, currentCursorRow * TILE_DIMENSION );
      catch(Exception exception ){
             System.out.println("exception in init method  --  "+exception.toString() );
    public void start(){
         Thread thread = new Thread(this);
         thread.start();         
    public void run(){
         while (true){
              // check game state;
              //checkState();
              // check the userinput
              checkUserInput();              
              updateScreen(g);
              flushGraphics();
              try{
                   Thread.currentThread().sleep(300);
              }catch(Exception exception){}
    private void checkUserInput(){
         int keyState = getKeyStates();
         switch(keyState){
              case FIRE_PRESSED:
                   if (selected){
                        selected = false;
                        // make the move
                        logging ("selected >>  row  "+selectedRow+"  column   >>  "+selectedColumn +"\n");
                        logging ("current >>  row   "+currentCursorRow+"  column   >>  "+currentCursorColumn +"\n");
                         int selectedItem = chessElements.getCell(selectedRow,selectedColumn);
                         logging("selected item  >>  "+selectedItem+"\n");
                         chessElements.setCell(currentCursorRow,currentCursorColumn,selectedItem);
                         chessElements.setCell(selectedRow,selectedColumn,0);
                         chessElements.setCell(6,6,7);
                         logging ("selected >>  row  "+selectedRow+"  column   >>  "+selectedColumn +"\n");
                        moveCursor(0,0);
                   }else{
                        selected = true;
                        selectedRow = currentCursorRow;
                        selectedColumn = currentCursorColumn;
                        chessElements.setCell(6,6,7);
                   animateSelectedItem();
              break;
              case UP_PRESSED:
                   if (!cursor.isVisible())
                        cursor.setVisible(true);          
                   if (currentCursorRow == 1){
                        if (currentCursorColumn == 8){
                             currentCursorColumn =1;
                             currentCursorRow = 8;
                             currentPixelX = -112;
                             currentPixelY = 112;
                             //moveCursor(-112,112);
                        }else{
                             currentCursorColumn++;
                             currentCursorRow = 8;
                             currentPixelX = TILE_DIMENSION;
                             currentPixelY = 112;
                             //moveCursor(TILE_DIMENSION,112);
                   else{
                        currentCursorRow--;
                        currentPixelX = 0;
                        currentPixelY = -TILE_DIMENSION;
                        //moveCursor(0,-TILE_DIMENSION);
                   moveCursor(currentPixelX,currentPixelY);
              break;
              case DOWN_PRESSED:
                   if (!cursor.isVisible())
                        cursor.setVisible(true);
                   if (currentCursorRow == 8){
                        if (currentCursorColumn == 8){
                             currentCursorColumn =1;
                             currentCursorRow = 1;
                             currentPixelX = -112;
                             currentPixelY = -112;
                             //moveCursor(-112,-112);
                        }else{
                             currentCursorColumn++;
                             currentCursorRow = 1;
                             currentPixelX = TILE_DIMENSION;
                             currentPixelY = -112;
                             //moveCursor(TILE_DIMENSION,-112);
                   else{
                        currentCursorRow++;
                        currentPixelX = 0;
                        currentPixelY = TILE_DIMENSION;
                        //moveCursor(0,TILE_DIMENSION);
                   moveCursor(currentPixelX, currentPixelY);
              break;
              case LEFT_PRESSED:
                   if (!cursor.isVisible())
                       cursor.setVisible(true);
                   if (currentCursorColumn == 1){
                        if (currentCursorRow == 1){
                             currentCursorColumn =8;
                             currentCursorRow = 8;
                             currentPixelX = 112;
                             currentPixelY = 112;
                             //moveCursor(112,112);
                        }else{
                             currentCursorColumn = 8;
                             currentCursorRow--;
                             currentPixelX = 112;
                             currentPixelY = -TILE_DIMENSION;                       
                             //moveCursor(112,-TILE_DIMENSION);
                   else{
                        currentCursorColumn--;
                        currentPixelX = -TILE_DIMENSION;
                        currentPixelY = 0;
                        //moveCursor(-TILE_DIMENSION,0);
                        moveCursor(currentPixelX, currentPixelY);
              break;
              case RIGHT_PRESSED:
                   if (!cursor.isVisible())
                       cursor.setVisible(true);
                   if (currentCursorColumn == 8){
                        if (currentCursorRow == 8){
                             currentCursorColumn =1;
                             currentCursorRow = 1;
                             currentPixelX = -112;
                             currentPixelY = -112;
                             //moveCursor(-112,-112);
                        }else{
                             currentCursorColumn = 1;
                             currentCursorRow++;
                             currentPixelX = -112;
                             currentPixelY = TILE_DIMENSION;
                             //moveCursor(-112,TILE_DIMENSION);
                   else{
                        currentCursorColumn++;
                        currentPixelX = TILE_DIMENSION;
                        currentPixelY = 0;
                        //moveCursor(TILE_DIMENSION,0);
                   moveCursor(currentPixelX,currentPixelY);
              break;
    public void updateScreen(Graphics g){
         g = getGraphics();
         // set the background color
         g.setColor(white);
         g.fillRect(0, 0, getWidth(), getHeight());
          // draw the board         
         tiledLayer.paint(g);
         // paint the cursor
         cursor.paint(g);
         // chess elements
         chessElements.paint(g);
    private void moveCursor(int x , int y){
         //logging(" cursor  >>   "+cursor.getFrame());
         // red cursor selected
         if (selected){
              //logging("red");
              cursor.setFrame(1);
         }else{
              // normal green cursor moving
              //logging("green");
              cursor.setFrame(0);
         cursor.move(x,y);
     * Animate the selected Item. runs a saperate thread;
    private void animateSelectedItem(){
         cursor.setVisible(false);
         new Thread(new Runnable() {
              Graphics g = getGraphics();
              public void run(){
                       while(selected){
                        try{
                             Thread.currentThread().sleep(600);
                        }catch(Exception exception){
                             System.out.println("exception in animating sprite");
                         g.setColor(0xF71302);
                         g.drawRect((startX+ (selectedColumn * TILE_DIMENSION))-16,
                                        (startY+ (selectedRow * TILE_DIMENSION))-16, 14, 14 );
                        flushGraphics();
         }).start();
    private void logging (String str){
         System.out.print(str);
}plz help me....
thanks :(

Answer 1

{color:#000080}I don't know whether that's the only thing wrong here, but I see 3 calls to getGraphics(). The documentation for javax.microedition.lcdui.game.GameCanvas.getGraphics() says:{color}
A new Graphics object is created and returned each time this method is called; therefore, the needed Graphics object(s) should be obtained before the game starts then re-used while the game is running.
{color:#000080}-- Your call to getGraphics() in updateScreen(Graphics g) will return the reference to the local variable represented by the parameter g, which will be out of scope as soon as the method returns.
-- Your call to getGraphics() in animateSelectedItem() assigns the reference to a newly declared local variable, which too will be out of scope when the method returns. (But this method includes flushGraphics() so just possibly this g is flushed to the display.)
db{color}