Question

我已经用RecyclerView创建了一个应用程序，但是在装有4.1 Android OS的设备中它崩溃了。有RecyclerView的替代方法，还是我可以解决问题？

谢谢。

更新

活动

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class Dashboard extends AppCompatActivity {

    private Activity activity;

    private SharedPreferences pref;
    SharedPreferences shared;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        pref = getPreferences(0);

        Fragment fragment;
        fragment = new DashboardFragment();
        FragmentTransaction ft = getFragmentManager().beginTransaction();
        ft.replace(R.id.fragment_frame, fragment);
        ft.commit();

    }//fine OnCreate


}// FINE CLASS

片段

import android.app.ProgressDialog;
import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.support.annotation.Nullable;
import android.support.design.widget.Snackbar;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;

import com.xxx.parser.JSONParser;
import com.xxx.utils.InternetConnection;
import com.xxx.utils.Keys;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class  FragmentCards extends android.app.Fragment {

    View v;
    private RecyclerView myrecyclerview;
    private List<Cards> lstCards;
    //

    private SharedPreferences pref;
    SharedPreferences shared;
    String unique_id;

    // Getting application context
    Context context = getActivity();

    //JSON
    private ListView listView;
    RecyclerViewAdapter recyclerAdapter;


    public FragmentCards() {
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        v = inflater.inflate(R.layout.cards_fragment, container, false);
        myrecyclerview = (RecyclerView) v.findViewById(R.id.card_rv);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            recyclerAdapter = new RecyclerViewAdapter(getContext(),lstCards);
        }
        myrecyclerview.setLayoutManager(new LinearLayoutManager(getActivity()));
        myrecyclerview.setAdapter(recyclerAdapter);
        return v;
//        return null;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //per visualizzare codice
        pref = getActivity().getPreferences(0);
        shared = getActivity().getSharedPreferences("A", Context.MODE_PRIVATE);   // get the sharedpreference set named "A"
        unique_id= shared.getString("unique_id","");
//
//
        lstCards = new ArrayList<>();
//
        goToList();

    } // fine ON CREATE

    public void check_connectivity(){
        View view = getActivity().findViewById(android.R.id.content);
        // Initialize a new Snackbar
        Snackbar snackbar = Snackbar.make(view, "Connessione assente ... riprovo fra 5 secondi", Snackbar.LENGTH_INDEFINITE);
        // Change the Snackbar default background color
        View snackbarView = snackbar.getView();
        snackbarView.setBackgroundColor(Color.parseColor("#FF0000"));
        snackbar.show();

        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                View view = getActivity().findViewById(android.R.id.content);
                Snackbar snackbar = Snackbar.make(view, "Connessione in corso ...", Snackbar.LENGTH_SHORT);
                // Change the Snackbar default background color
                View snackbarView = snackbar.getView();
                snackbarView.setBackgroundColor(Color.parseColor("#F9A603"));
                snackbar.show();
                new Handler().postDelayed(new Runnable() {
                    @Override
                    public void run() {

                        goToList();

                    }
                }, 1500);

            }
        }, 5000);
    }

    public void goToList() {
        if (InternetConnection.checkConnection(getActivity().getApplicationContext())) {

            new GetDataTask().execute();
            View view = getActivity().findViewById(android.R.id.content);
            Snackbar snackbar = Snackbar.make(view, "Connesso", Snackbar.LENGTH_SHORT);
            // Change the Snackbar default background color
            View snackbarView = snackbar.getView();
            snackbarView.setBackgroundColor(Color.parseColor("#258039"));
            snackbar.show();

        } else {
            check_connectivity();

        }
    }

    class GetDataTask extends AsyncTask<Void, Void, Void> {

        ProgressDialog dialog;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            dialog = new ProgressDialog(getActivity());
            dialog.setTitle("Un attimo di pazienza...");
            dialog.setMessage("Carico le tue card");
            dialog.show();
        }

        @Nullable
        @Override
        protected Void doInBackground(Void... params) {

            JSONObject jsonObject = JSONParser.getDataById(unique_id);


            try {


                        JSONArray array = jsonObject.getJSONArray(Keys.KEY_CONTACTS);


                        int lenArray = array.length();
                        if(lenArray > 0) {
                            for(int jIndex = 0; jIndex < lenArray; jIndex++) {


                                JSONObject innerObject = array.getJSONObject(jIndex);
                                String desc_dist = innerObject.getString(Keys.KEY_DIST);
                                String numero_card = innerObject.getString(Keys.KEY_NUM_CARD);
                                String totpunti_card = innerObject.getString(Keys.KEY_TOT_PUNTI);
                                String id_cd = innerObject.getString(Keys.KEY_ID_CD);


                                /**
                                 * Adding name and phone concatenation in List...
                                 */
                                lstCards.add(new Cards( numero_card,desc_dist,totpunti_card,id_cd) );
                            } //fine FOR

                        }
                    }
                } else {

                }
            } catch (JSONException je) {
                Log.i(JSONParser.TAG, "" + je.getLocalizedMessage());
            }
            return null;
        } // FINE doBackground

        @Override
        protected void onPostExecute(Void aVoid) {
            super.onPostExecute(aVoid);
            dialog.dismiss();
            /**
             * Checking if List size if more than zero then
             * Update ListView
             */
            if(lstCards.size() > 0) {
                recyclerAdapter.notifyDataSetChanged();
            } else {
                View view = getActivity().findViewById(android.R.id.content);
                Snackbar snackbar = Snackbar.make(view, "No Data Found", Snackbar.LENGTH_SHORT);
            }
        }
    } // fine GetDataTask
}

RecyclerView

    import android.app.Activity;
    import android.app.Dialog;
    import android.app.Fragment;
    import android.content.Context;
    import android.support.annotation.NonNull;
    import android.support.v7.widget.RecyclerView;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.LinearLayout;
    import android.widget.TextView;
    import android.widget.Toast;

    import java.util.List;

    public class RecycleTransCardAdapter extends RecyclerView.Adapter<RecycleTransCardAdapter.MyViewHolder> {


        Context mContext;
        List<InfoCard> mData;
        Dialog myDialog;

        public RecycleTransCardAdapter(Context mContext, List<InfoCard> mData) {
            this.mContext = mContext;
            this.mData = mData;
        }

        @NonNull
        @Override
        public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

            View v;
            v = LayoutInflater.from(mContext).inflate(R.layout.item_trans_card, parent, false);
            final MyViewHolder vHolder = new MyViewHolder(v);


            return vHolder;
        }

        @Override
        public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {

// some code
        }

        @Override
        public int getItemCount() {
            return mData.size();
        }

        public static class MyViewHolder extends RecyclerView.ViewHolder {

// some code


            public MyViewHolder(View itemView) {
                super(itemView) ;
// some code

            }
        }

    }

此行中的片段中有错误：

recyclerAdapter.notifyDataSetChanged（）;

我仅在旧OS Android上有此错误示例：4.1版本

Answer 1

recyclerview是向后兼容的，前提是您在应用程序的build.gradle文件中包括了RecyclerView v7的支持库：

compile "com.android.support:recyclerview-v7:21.0.0.+"

该版本将在Android 2.1（API级别7）下运行，因此命名为v7

因此，您可以在运行速度低于Android 2.1（API级别7）的设备上使用recyclerview，因此名称为v7

尝试添加上述库，如果仍然崩溃，则再次运行应用程序使用应用程序的错误日志更新问题。

Answer 2

RecyclerView是支持库的一部分，您也可以在较旧的设备上使用它。尝试使用AndroidX软件包<HttpPost()> 而不是支持库。

androidx.recyclerview.widget.RecyclerView

有关AndroidX的更多详细信息，请访问以下地址： https://developer.android.com/jetpack/androidx/

旧版SDK的RecyclerView替代品

2 个答案: