Exception caught in Display class

Hey Hi Friends I got Error in my code. My Project compiling Successfully & Running from starting good but when I am Firing Mobile Middle key that time it shows error like that.....

TRACE: <at java.lang.Error: ClassFormatError:  56>, Exception caught in Display class
java.lang.Error: ClassFormatError:  56
        at java.lang.Class.invoke_verify(), bci=0
        at java.lang.Class.initialize(), bci=117
        at com.ui.PreviewPageUI.getPreviewData(), bci=0
        at com.ui.PreviewPageUI.keyPressedMainCatFire(), bci=54
        at com.ui.PreviewPageUI.keyPressedFire(PreviewPageUI.java:451)
        at com.ui.PreviewPageUI.keyPressed(PreviewPageUI.java:284)
        at javax.microedition.lcdui.CanvasLFImpl.uCallKeyPressed(), bci=19
        at javax.microedition.lcdui.DisplayableLFImpl.uCallKeyEvent(), bci=146
        at javax.microedition.lcdui.Display$DisplayEventConsumerImpl.handleKeyEvent(), bci=30
        at com.sun.midp.lcdui.DisplayEventListener.process(), bci=277
        at com.sun.midp.events.EventQueue.run(), bci=179
        at java.lang.Thread.run(Thread.java:662)

Please help me how to remove this error... Thanks This is my Function Code

private void getPreviewData(final String cat) {
        Thread th = new Thread() {

            public void run() {
                try {
                    if (cat.equals("VD")) {
                        if (videoHastable == null || videoHastable.isEmpty()) {
                            initializeWaiting();
                            ParseUrl parsedata=new ParseUrl();
                       开发者_如何学编程     json=new JSONObject();
                            try {
                                json.put("phonetype",Midlet.PHONE_TYPE);
                                json.put("cat","VD");
                            } catch (JSONException ex) {
                                System.out.println(ex.toString());
                            }
                            String url="http://localhost:8084/MagicWeb/pappilon1?json="+json.toString();

                            videoHastable =parsedata.coonectHttp(url,cat);
                            circularLoading = false;
                        }
                        if (videoHastable != null) {
                            Midlet.display.setCurrent(new WallPapersCanvas(2, "VIDEOS", videoHastable));
                        } else {
                            initializeError("MESSAGE", "COULD NOT POPULATE DATA FROM THE SERVER", MAIN_CATEGORIES);
                        }
                    } else if (cat.equals("WP")) {
                        if (wallHastable == null || wallHastable.isEmpty()) {
                            initializeWaiting();

                            ParseUrl parsedata=new ParseUrl();
                            json=new JSONObject();
                            try {
                                json.put("phonetype",Midlet.PHONE_TYPE);
                                json.put("cat","WP");
                            }catch(JSONException e){
                                System.out.println("json excep:"+e.toString());
                            }catch(Exception e){
                                System.out.println("error in wp getpriview:"+e.toString());
                            }
                            String url="http://localhost:8084/MagicWeb/pappilon1?json="+json.toString();
                            System.out.println("I am in wallpaper getpreiview");
                            wallHastable =parsedata.coonectHttp(url,cat);
                            circularLoading = false;
                        }
                        if (wallHastable != null) {
                            Midlet.display.setCurrent(new WallPapersCanvas(2, "WALLPAPERS", wallHastable));
                        } else {
                            initializeError("MESSAGE", "COULD NOT POPULATE DATA FROM THE SERVER", MAIN_CATEGORIES);
                        }
                    } else if (cat.equals("GM")) {
                        if (gamesHastable == null || gamesHastable.isEmpty()) {
                            initializeWaiting();

                            ParseUrl parsedata=new ParseUrl();
                            json=new JSONObject();
                            try {
                                json.put("phonetype",Midlet.PHONE_TYPE);
                                json.put("cat","GM");
                            } catch (JSONException ex) {
                                System.out.println(ex.toString());
                            }
                            String url="http://localhost:8084/MagicWeb/pappilon1?json="+json.toString();
                            gamesHastable =parsedata.coonectHttp(url,cat);
                            circularLoading = false;
                        }
                        if (gamesHastable != null) {
                            Midlet.display.setCurrent(new WallPapersCanvas(2, "GAMES", gamesHastable));
                        } else {
                            initializeError("MESSAGE", "COULD NOT POPULATE DATA FROM THE SERVER", MAIN_CATEGORIES);
                        }
                    } else if (cat.equals("TH")) {
                        if (themesHastable == null || themesHastable.isEmpty()) {
                            initializeWaiting();

                            ParseUrl parsedata=new ParseUrl();
                            json=new JSONObject();
                            try {
                                json.put("phonetype",Midlet.PHONE_TYPE);
                                json.put("cat","TH");
                            } catch (JSONException ex) {
                                System.out.println(ex.toString());
                            }
                            String url="http://localhost:8084/MagicWeb/pappilon1?json="+json.toString();
                            themesHastable =parsedata.coonectHttp(url,cat);
                            circularLoading = false;
                        }
                        if (themesHastable != null) {
                            Midlet.display.setCurrent(new WallPapersCanvas(2, "THEMES", themesHastable));
                        } else {
                            initializeError("MESSAGE", "COULD NOT POPULATE DATA FROM THE SERVER", MAIN_CATEGORIES);
                        }
                    } else if (cat.equals("AN")) {
                        if (animateHastable == null || animateHastable.isEmpty()) {
                            initializeWaiting();

                            ParseUrl parsedata=new ParseUrl();
                            json=new JSONObject();
                            try {
                                json.put("phonetype",Midlet.PHONE_TYPE);
                                json.put("cat","AN");
                            } catch (JSONException ex) {
                                System.out.println(ex.toString());
                            }
                            String url="http://localhost:8084/MagicWeb/pappilon1?json="+json.toString();
                            animateHastable =parsedata.coonectHttp(url,cat);
                            circularLoading = false;
                        }
                        if (animateHastable != null) {
                            Midlet.display.setCurrent(new WallPapersCanvas(2, "ANIMATIONS", animateHastable));
                        } else {
                            initializeError("MESSAGE", "COULD NOT POPULATE DATA FROM THE SERVER", MAIN_CATEGORIES);
                        }
                    } else if (cat.equals("FS")) {
                        if (freeHastable == null || freeHastable.isEmpty()) {
                            initializeWaiting();

                            ParseUrl parsedata=new ParseUrl();
                            json=new JSONObject();
                            try {
                                json.put("phonetype",Midlet.PHONE_TYPE);
                                json.put("cat","FS");
                            } catch (JSONException ex) {
                                System.out.println(ex.toString());
                            }
                            String url="http://localhost:8084/MagicWeb/pappilon1?json="+json.toString();
                            freeHastable =parsedata.coonectHttp(url,cat);
                            circularLoading = false;
                        }
                        if (freeHastable != null) {
                            Midlet.display.setCurrent(new WallPapersCanvas(2, "FREE GIFTS", freeHastable));
                        } else {
                            initializeError("MESSAGE", "COULD NOT POPULATE DATA FROM THE SERVER", MAIN_CATEGORIES);
                        }
                    } else {
                        initializeError("MESSAGE", "CATEGORY NAME DOES NOT EXIST", MAIN_CATEGORIES);
                    }
                } catch (Exception e) {
                    System.out.println("error @ getPreviewData");
                    e.printStackTrace();
                }
            }
        };
        th.start();
    }

Thrown when the Java Virtual Machine attempts to read a class file and determines that the file is malformed or otherwise cannot be interpreted as a class file.

Link ... Could you please put your code?