Android活动会重新创建

Question

我的应用程序通常工作正常,直到我在特定设备上遇到一个奇怪的问题.App中有2项活动.在ActivityA中启动ActivityB后,ActivityA启动没有问题.但是,在我通过推回硬件按钮或调用finish()返回ActivityA之后; 在ActivityB中的closeButton内部,ActivityA重新加载自身.它再次触发onCreate()并重新加载其所有内容.而且我没有改变手机的方向.这种奇怪的行为只出现在超过1.000下载app的15部手机中.

此问题仅发生在Galaxy S3 Android OS 4.1.2上.这也很奇怪.

你知道为什么会这样吗？

当我在按钮监听器中启动一个新的Activity时,如下所示:

ActivityA.java(MesajlarListViewActivity)

    public class MesajlarListViewActivity extends TrackedActivity {

    Context context = null;

    // contacts JSONArray
    JSONArray contacts = null;

    ArrayList<Message> productArray = new ArrayList<Message>();

    private ProductAdapter adapter;
    private ListView productList;
    private Runnable viewOrders;
    private HoloProgressIndicator profilInfoProgress = null;

    ImageView kapatButton = null;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mesajlar_list);

        context = this;

        kapatButton = (ImageView) findViewById(R.id.kapat_button);
        /* kapat button onclick listener. */
        // =================================================================================================================
        kapatButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view)
            {
                // Set vibration on touch.
                KnetGenericClass.vibratePhone(context);

                finish();
            }

        });
        // =================================================================================================================
        //Progress bar.
        profilInfoProgress = (HoloProgressIndicator) findViewById(R.id.profil_info_progress);

        // cheking internet connectivity.
        if(KnetGenericClass.checkInternetConnection(context))
        {
            // start task!
            /* internet var ise web service baglantisi kurmaya baslayabiliriz. */
            startActivityIndicatorWithThread();
        }
        else
        {
            KnetGenericClass.printErrorMessage(context, "Ba?lant? Hatas?",
                    "Lütfen internet ba?lant?n?z? kontrol ediniz.");
        }

        productList = (ListView) findViewById(R.id.product_list);
        adapter = new ProductAdapter(this, R.layout.message_row, productArray);
        productList.setAdapter(adapter);

        // When user click a view on list view new page is appearing.
        productList.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view, int position, long id)
            {

                // Set vibration on touch.
                KnetGenericClass.vibratePhone(context);

                /* Navigate to message detay activity class with ilan ID. */
                Intent myIntent = new Intent(view.getContext(), MesajDetayActivity.class);
                myIntent.putExtra("messageID", productArray.get(position).getId());
                startActivity(myIntent);

                // setting image of clicked message null.
                RelativeLayout relativeLayout = (RelativeLayout) view;
                ImageView unreadedImageView = (ImageView) relativeLayout.findViewById(R.id.unreaded_image);
                unreadedImageView.setImageResource(0);
            }
        });
    }

    public class ProductAdapter extends ArrayAdapter<Message> {
        ArrayList<Message> items;

        public ProductAdapter(Context context, int textViewResourceId, ArrayList<Message> objects) {
            super(context, textViewResourceId, objects);
            this.items = objects;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent)
        {
            if(convertView == null)
            {
                LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = vi.inflate(R.layout.message_row, null);
            }

            ImageView unreadedImageView = (ImageView) convertView.findViewById(R.id.unreaded_image);
            TextView productName = (TextView) convertView.findViewById(R.id.product_name);
            TextView productDetail = (TextView) convertView.findViewById(R.id.product_detail);
            // TextView productDate = (TextView)
            // convertView.findViewById(R.id.product_date);
            TextView sentDate = (TextView) convertView.findViewById(R.id.product_date);

            productName.setText(items.get(position).getSender());
            productDetail.setText(items.get(position).getTitle());
            // String bodyNoHTML = items.get(position).getBody();

            if(items.get(position).getIsReaded())
            {
                unreadedImageView.setImageResource(0);
            }
            else
            {
                unreadedImageView.setImageResource(R.drawable.bluedot);
            }

            String dateStr = items.get(position).getSentDate();
            try
            {
                sentDate.setText(dateStr.substring(6, 8) + "." + dateStr.substring(4, 6) + "." + dateStr.substring(0, 4)
                        +" "+dateStr.substring(8, 10)+":"+dateStr.substring(10, 12));
            }
            catch(Exception e)
            {
                sentDate.setText("");
            }


            return convertView;
        }

    }// @end of product adapter class.

    /* web service'e baglanti kurulan methodu threadin icerisinde cagiriyoruz. */
    public void startActivityIndicatorWithThread()
    {
        // ==============================================================================================
        // getting ilan details into arraylist.
        // setting up thread.
        viewOrders = new Runnable() {
            public void run()
            {
                getMessageListFromWebService();
            }
        };
        Thread thread = new Thread(null, viewOrders, "MagentoBackground");
        thread.start();
        profilInfoProgress.start();
        // ==============================================================================================
        // @end of the thread declaration.
    }

    public void getMessageListFromWebService()
    {
        // Creating JSON Parser instance
        JSONParser jParser = new JSONParser(context);

        // getting JSON string from URL
        JSONArray jsonArray = jParser.getAuthorizedInfoFromUrlToJSONArray(
                WebServiceInfo.getKnetWebServiceLink()+"/API/Member/GetInboxMessageList", MainActivity.getAccessToken());

        // if json is null then there is a problem.
        if(jsonArray == null)
        {
            // if json array is null then print error message.
            runOnUiThread(showAlertMessage);
            runOnUiThread(returnRes);
            return;
        }

        try
        {
            // Eger aranilan kritere gore ilan yok ise hata mesaji basiyoruz.
            if(jsonArray.length() == 0)
            {
                // if json array is null then print error message.
                runOnUiThread(showAlertIlanYokMessage);
                runOnUiThread(returnRes);
                return;
            }

            // looping through All Contacts
            for (int i = 0; i < jsonArray.length(); i++)
            {
                JSONObject c = jsonArray.getJSONObject(i);

                // Storing each json item in variable
                // String id = c.getString(TAG_ID);
                String id = c.getString("Id");
                String sender = c.getString("Sender");
                // String body = c.getString("Body");
                String title = c.getString("Title");
                String sentDate = c.getString("SentDate");
                Boolean isReaded = c.getBoolean("IsRead");

                Message productObject = new Message(id, sender, "", title, sentDate, isReaded);
                productArray.add(productObject);
            }
        }
        catch (Exception e)
        {
            Log.e("BACKGROUND_PROC", e.getMessage());
        }
        runOnUiThread(returnRes);
    }


    // @end of thread.
    private Runnable returnRes = new Runnable() {

        public void run()
        {
            profilInfoProgress.stop();
            adapter.notifyDataSetChanged();// refreshing data over adapter in
                                            // list view.
        }
    };

    // @end of thread.
    private Runnable showAlertMessage = new Runnable() {

        public void run()
        {
            // Bu hata genelde linkteki problemden, servera ulasilamamasindan
            // veya timeouttan meydana gelir.
            Toast.makeText(getApplicationContext(),
                    "Mesajlar al?namad? lütfen daha sonra tekrar deneyiniz.", 
                    Toast.LENGTH_LONG).show();
        }
    };

    private Runnable showAlertIlanYokMessage = new Runnable() {

        public void run()
        {
            // Bu hata aranilan kelimeye gore ilan bulunamazsa gelir.
            Toast.makeText(getApplicationContext(),
                    "Mesajlar bulunamad?.", 
                    Toast.LENGTH_LONG).show();
        }
    };

}

================================================== ======================

ActivityB.java(MesajDetayActivity.java)

public class MesajDetayActivity extends TrackedActivity {

    private HoloProgressIndicator profilInfoProgress = null;

    TextView titleTextView = null;
    TextView senderTextView = null;
    TextView dateTextView = null;
    WebView bodyWebView = null;

    Message messageObject = null;

    String messageID = null;

    ImageView kapatButton = null;

    Context context;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mesajdetaylari);

        context = this;

        kapatButton = (ImageView) findViewById(R.id.kapat_button);
        /* kapat button onclick listener. */
        // =================================================================================================================
        kapatButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view)
            {
                // Set vibration on touch.
                KnetGenericClass.vibratePhone(context);

                finish();
            }

        });
        // =================================================================================================================
        //Progress bar.
        profilInfoProgress = (HoloProgressIndicator) findViewById(R.id.profil_info_progress);

        Bundle extras = getIntent().getExtras();
        if(extras != null)
        {
            messageID = extras.getString("messageID");
        }

        titleTextView = (TextView) findViewById(R.id.title_textview);
        senderTextView = (TextView) findViewById(R.id.sender_textview);
        dateTextView = (TextView) findViewById(R.id.date_textview);
        bodyWebView = (WebView) findViewById(R.id.mesaj_webView);

        // Show the ProgressDialog on this thread
        profilInfoProgress.start();

        // Start a new thread that will download all the data
        new MakeItTask().execute();

    }

    // Async task.
    private class MakeItTask extends AsyncTask<String, Void, Object> {
        protected Object doInBackground(String... args)
        {
            Log.i("MyApp", "Background thread starting");

            // This is where you would do all the work of downloading your data
            // getting message detay
            /* connect to web service */
            getMessageDetayFromWebService();

            return null;
        }

        protected void onPostExecute(Object result)
        {
            // Pass the result data back to the main activity
            // TakipListeActivity.this.data = result;
            try
            {
                titleTextView.setText("Ba?l?k: " + messageObject.getTitle());
                senderTextView.setText("Gönderen: " + messageObject.getSender());
                dateTextView.setText("Tarih: " + messageObject.getSentDate().substring(6, 8) + "."
                        + messageObject.getSentDate().substring(4, 6) + "."
                        + messageObject.getSentDate().substring(0, 4));

                if(!messageObject.getBody().contains("img"))
                {
                    bodyWebView.loadDataWithBaseURL(null, messageObject.getBody(), "text/html", "UTF-8", null);
                }

            }
            catch (Exception e)
            {
                Log.e(CONNECTIVITY_SERVICE, "Mesaj Detayi bilgileri basilamadi.");
            }

            profilInfoProgress.stop();
        }
    }

    /* web service'e baglanti kurulan methodu threadin icerisinde cagiriyoruz. */
    public void getMessageDetayFromWebService()
    {
        // Creating JSON Parser instance
        JSONParser jParser = new JSONParser(context);

        // getting JSON string from URL
        JSONObject jsonObject = jParser.getAuthorizedInfoFromUrlToJSONObject(
                WebServiceInfo.getKnetWebServiceLink()+"/API/Member/GetInboxMessage/" + messageID, MainActivity.getAccessToken());

        // if json is null then there is a problem.
        if(jsonObject == null)
        {
            return;
        }

        try
        {
            String title = jsonObject.getString("Title");
            String id = jsonObject.getString("Id");
            String sender = jsonObject.getString("Sender");
            String date = jsonObject.getString("SentDate");
            String body = jsonObject.getString("Body");

            messageObject = new Message(id, sender, body, title, date, true);

        }
        catch (Exception e)
        {
            Log.e("BACKGROUND_PROC", e.getMessage());
        }

    }// @end of getIlanDetayFromWebService.

}

编辑:不仅这两个活动有这个问题,所有活动在某些手机上的行为相同.

Answer 1

检查是否在"设置" >" 系统" >" 开发人员选项" >" 应用程序"下保持活动.

Answer 2

活动文档(http://developer.android.com/reference/android/app/Activity.html)说明了有关后台活动生命周期的以下内容:

后台活动(用户不可见且已暂停的活动)不再重要,因此系统可以安全地终止其进程以回收其他前台或可见进程的内存.如果需要杀死它的进程,当用户导航回活动(再次在屏幕上显示)时,将使用之前在onSaveInstanceState(Bundle)中提供的savedInstanceState调用其onCreate(Bundle)方法,以便它可以在用户上次离开的状态下重启自己.

换句话说,当ActivityB处于活动状态时,ActivityA可能会或可能不会被操作系统销毁,因此必须在代码中处理这种情况.如果ActivityA已被销毁,则当用户按下ActivityB中的后退按钮时,将调用onCreate(Bundle).

Answer 3

有一个名为"不要保持活动"的Android开发人员设置.此选项的描述是"用户离开时立即销毁每个活动".这听起来像是对你所看到的内容的一个很好的描述,并且因为你只是在几部手机上看到这个由非默认系统设置引起的想法似乎是合理的.

理想情况下,您的应用程序仍然可以在这种情况下工作,即使不是最佳.但是,如果此设置对您的应用程序有疑问,您可能希望为您的用户记录此问题.

Answer 4

您是否尝试过更改launchmodeAndroid Manifest？尝试将此添加到您的活动声明中:

android:launchMode="singleTask"

接下来,尝试使用startActivityForResult,而不是startActivity.这将强制活动A onActivityResult(int, int, Intent)在活动B完成时调用其方法 - 这可能会跳过此(错误)调用onCreate.然后,在Activity A中,实现该方法以执行某些操作(例如打印调试语句):

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    Log.i("Test", "Did this work???");
    //TODO send notification to your server to verify this works?
}

Answer 5

我没有看到这种行为有任何问题.

如果您希望保持状态ActivityA,请使用方法onSaveInstanceState和onRestoreInstanceState.有关详细信息,请参阅http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle上的活动生命周期.

有关更深入的了解,另请参阅/sf/answers/734507721/.