RecyclerView Activity 返回后被殺死

Question

我已經放了一個 recyclerview，它顯示了一些包含文本和圖像的卡片。 卡片是可點擊的，並將用戶引導至另一個活動以查看卡片內容。 但是當用戶返回搜索活動時，recyclerview 會刪除這些項目。 它顯示未找到項目，因為如果異步任務返回結果無效，我已放置文本未找到項目。

提前致謝。

我已經包含了下面的代碼：

 @Override
public void onRestart() {
    super.onRestart();
    if(!cd.isConnectingToInternet()){
        alert.showAlertDialog(pgrentertabsearch.this,
                "No Internet Connection",
                "Please connect to Internet", false);
        // stop executing code by return
        return;

    }
    else {

        search(areavalue, pricevalue, numberofbedsvalue);
    }


}












private void search(final String searcharea, final String searchprice, final String searchnumberofbeds) {


    class PGAsync extends AsyncTask<String, Void, String> {

        private Dialog loadingDialog;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            spinner.setVisibility(View.VISIBLE);
            loading.setVisibility(View.VISIBLE);
        }

        @Override
        protected String doInBackground(String... params) {
            String searcharea = params[0];
            String searchprice = params[1];
            String searchnumberofbeds = params[2];

            InputStream is = null;
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
            nameValuePairs.add(new BasicNameValuePair("searcharea", searcharea));
            nameValuePairs.add(new BasicNameValuePair("searchprice", searchprice));
            nameValuePairs.add(new BasicNameValuePair("searchnumberofbeds", searchnumberofbeds));
            String result = null;

            try {
                HttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(
                        "http://xxx.php");
                httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

                HttpResponse response = httpClient.execute(httpPost);

                HttpEntity entity = response.getEntity();

                is = entity.getContent();

                BufferedReader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"), 8);
                StringBuilder sb = new StringBuilder();

                String line = null;
                while ((line = reader.readLine()) != null) {
                    sb.append(line + "\n");
                }
                result = sb.toString();
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return result;
        }

        @Override
        protected void onPostExecute(String result) {
            String s = jsonresult.trim();
    spinner.setVisibility(View.GONE);
                loading.setVisibility(View.GONE);
            if (!s.equalsIgnoreCase("invalid")) {
                found.setVisibility(View.VISIBLE);
                myJSON = result;
                showList();


            } else {
                pgnotfound.setVisibility(View.VISIBLE);
                pgnotfound1.setVisibility(View.VISIBLE);
                pgnotfoundimage.setVisibility(View.VISIBLE);


            }

        }
    }

    PGAsync g = new PGAsync();
    g.execute(searcharea, searchprice, searchnumberofbeds);


}


protected void showList() {


    try {
        JSONObject jsonObj = new JSONObject(myJSON);

        pgarray = jsonObj.getJSONArray(TAG_RESULTS);
        for(int i=0;i<pgarray.length();i++){
            JSONObject c = pgarray.getJSONObject(i);
            PGCardItemReturn pgcarditemreturn = new PGCardItemReturn();
            pgcarditemreturn.setId(c.getString(TAG_ID));



            pgcarditemreturn.setFurnishing(c.getString(TAG_FURNISHING));


            pgcarditemreturn.setArea(c.getString(TAG_AREA));

            pgcarditemreturn.setPrice(c.getString(TAG_PRICE));

            pgcarditemreturn.setNumberofbeds(c.getString(TAG_NUMBEROFBEDS));


            pgcarditemreturn.setImageUrl(c.getString(TAG_IMAGE_URL));


            listPG.add(pgcarditemreturn);



        }


    } catch (JSONException e) {
        e.printStackTrace();

    }
    adapter = new PGSearchCardAdapter(listPG, this);

    //Adding adapter to recyclerview
    recyclerView.setAdapter(adapter);


}

在 oncreate 方法中：

if(!cd.isConnectingToInternet()){
        alert.showAlertDialog(pgrentertabsearch.this,
                "No Internet Connection",
                "Please connect to Internet", false);
        // stop executing code by return
        return;

    }
    else {

        search(areavalue, pricevalue, numberofbedsvalue);
    }

她是 logcat：

11-28 15:56:06.377 1894-2620/eya.eya D/skia: --- SkImageDecoder::Factory returned null
11-28 15:56:07.552 1894-2619/eya.eya D/skia: --- SkImageDecoder::Factory returned null
11-28 15:56:07.843 1894-2620/eya.eya D/skia: --- SkImageDecoder::Factory returned null
11-28 15:56:08.858 1894-1936/eya.eya W/EGL_emulation: eglSurfaceAttrib not implemented
11-28 15:56:08.858 1894-1936/eya.eya W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xa3bb8020, error=EGL_SUCCESS
11-28 15:56:08.886 1894-1894/eya.eya E/RecyclerView: No adapter attached; skipping layout
11-28 15:56:08.898 1894-1894/eya.eya E/RecyclerView: No adapter attached; skipping layout
11-28 15:56:09.023 1894-1936/eya.eya D/OpenGLRenderer: endAllStagingAnimators on 0xa4349f00 (RippleDrawable) with handle 0xa3bffb50
11-28 15:56:09.233 1894-1894/eya.eya E/RecyclerView: No adapter attached; skipping layout
11-28 15:57:57.915 1894-1901/eya.eya W/art: Suspending all threads took: 5.356ms
11-28 16:02:08.480 1894-1901/eya.eya W/art: Suspending all threads took: 5.204ms
11-28 16:02:38.129 1894-1901/eya.eya W/art: Suspending all threads took: 5.316ms

Answer 1

如果我的理解是正確的，那么有兩個活動：

Activity A -> RecyclerView 顯示搜索結果

活動 B -> 每個回收商查看項目的詳細信息

---

當您從 Activity B 返回 Activity A 時，您的 Activity B 已被銷毀。

因此，您需要覆蓋 Activity A 中的 onSaveInstanceState(Bundle savedInstanceState) 和 onRestoreInstanceState(Bundle savedInstanceState)，以檢索您的數據列表。

例子：

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(outState);
savedInstanceState.putParcelable("key", myObject);
}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
Object myObject = savedInstanceState.getParcelable("key"); 
}

小心，你的對象類必須實現 Parcelable。

您可以查看文檔： http : //developer.android.com/reference/android/os/Parcelable.html

當您單擊“類概述”時，有一個典型的 Parcelable 實現。

還有一個自動實現 Parcelable 的工具：

http://dallasgutauckis.com/2012/01/20/parcelabler-for-implementing-androids-parcelable-interface/