带有asynctask android的sherlock片段

Question

我在AsyncTask中使用SherlockFragment并收到此错误并不知道原因

public class MainActivity extends SherlockFragmentActivity {

ViewPager vPager;
PageIndicator pIndicator;
ViewPagerAdapter mAdapter;
private Button cont;
private EditText email;
private HttpClassHandler handler;
private JSONObject jObj;
private static boolean SliderClick = true;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    strickMode();
    initialize();
    clicklistners();
}
@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
};

private void initialize() {
    mAdapter = new ViewPagerAdapter(getSupportFragmentManager());
    vPager = (ViewPager) findViewById(R.id.pager);
    pIndicator = (PageIndicator) findViewById(R.id.indicator);
    vPager.setAdapter(mAdapter);
    pIndicator.setViewPager(vPager);
    ((CirclePageIndicator) pIndicator).setSnap(true);
    email = (EditText) findViewById(R.id.email);
    cont = (Button) findViewById(R.id.continue_btn);
    handler = new HttpClassHandler();
    final Handler mHandler = new Handler();
    new Thread(new Runnable() {
        @Override
        public void run() {
            while (SliderClick) {
                try {
                    Thread.sleep(5000);
                    mHandler.post(new Runnable() {

                        @Override
                        public void run() {
                            if (vPager.getCurrentItem() == 5) {
                                vPager.setCurrentItem(0, true);
                            } else {
                                vPager.setCurrentItem(
                                        vPager.getCurrentItem() + 1, true);
                            }
                        }
                    });
                } catch (Exception e) {
                }
            }
        }
    }).start();
}

public void clicklistners() {
    vPager.setPageTransformer(false, new ViewPager.PageTransformer() {
        @Override
        public void transformPage(View page, float position) {
            final float normalizedposition = Math.abs(Math.abs(position) - 1);
            page.setScaleX(normalizedposition / 2 + 0.5f);
            page.setScaleY(normalizedposition / 2 + 0.5f);
        }
    });
    cont.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            final String user_mail = email.getText().toString();
            if (user_mail.equals("")) {
                AlertDialog.Builder d = new AlertDialog.Builder(
                        MainActivity.this);
                d.setTitle("Error");
                d.setIcon(R.drawable.signup_btn_bg);
                d.setMessage("Please Enter Your email");
                d.setNeutralButton("OK", null);
                d.create();
                d.show();
            } else {
                if (validateEmail(user_mail)) {

                    AsyncTask<Void, Void, Boolean> task = new AsyncTask<Void, Void, Boolean>() {
                        ProgressDialog progress;

                        @Override
                        protected void onPreExecute() {
                            super.onPreExecute();
                            progress = ProgressDialog.show(
                                    MainActivity.this, "Checking Login",
                                    "Please Wait...");
                        }

                        @Override
                        protected void onPostExecute(Boolean result) {
                            super.onPostExecute(result);
                            progress.dismiss();
                            if (result) {
                                Intent i = new Intent(MainActivity.this,
                                        SignInActicity.class);
                                startActivity(i);
                                MainActivity.this.onCreate(null);
                            } else {
                                try {
                                    Toast.makeText(MainActivity.this,
                                            jObj.getString("message"),
                                            Toast.LENGTH_LONG).show();
                                } catch (JSONException e) {
                                    e.printStackTrace();
                                }
                            }

                        }

                        @Override
                        protected Boolean doInBackground(Void... params) {
                            jObj = handler.checkMail(user_mail);
                            try {
                                String msg = jObj.getString("success")
                                        .toString();
                                if (msg.equals("1")) {
                                    return true;

                                } else if (msg.equals("0")) {
                                    return false;
                                }
                            } catch (JSONException e) {
                                Toast.makeText(MainActivity.this,
                                        "Error occurred", Toast.LENGTH_LONG)
                                        .show();
                                e.printStackTrace();
                            }
                            return false;
                        }

                    };
                    task.execute();

                } else {
                    Toast.makeText(MainActivity.this,
                            "Enter a Valid Email Address!",
                            Toast.LENGTH_LONG).show();
                }
            }
        }
    });
}

public static boolean validateEmail(String email) {
    boolean isValid = false;

    String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
    CharSequence inputStr = email;

    Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
    Matcher matcher = pattern.matcher(inputStr);
    if (matcher.matches()) {
        isValid = true;
    }

    return isValid;
}