android - 如何修复条形码扫描应用程序中的错误，发出网络请求时崩溃

Question

我正在 android studio 3.3.2 中开发一个 android 应用程序（条形码扫描仪）。我想将它与远程数据库链接，应用程序构建并成功运行，但是当我扫描条形码时，它崩溃，返回一个空活动。

我试图调试错误但无济于事，我是android studio的新手。我尝试使用凌空抽射。

Java包com.example.scan；

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.hardware.Camera;
import android.support.design.widget.CoordinatorLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.Color;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.helper.ItemTouchHelper;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.Toast;


import com.google.zxing.integration.android.IntentIntegrator;
import com.google.zxing.integration.android.IntentResult;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

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

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


public class MainActivity extends AppCompatActivity {

    private static final String URL_PRODUCTS = "http://192.168.43.232/Product/Api.php";
    public static final String MyPREFERENCES = "MyPrefs";
    RecyclerView recyclerView;
    ArrayList<ListItem> arrayList;
    MyAdapter myAdapter;
    CoordinatorLayout coordinatorLayout;
    RelativeLayout relativeLayout;
    List<ListItem> listItemsArrayList;
    SharedPreferences sharedpreferences;

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

        relativeLayout = (RelativeLayout) findViewById(R.id.ralativeLayout);
        recyclerView = (RecyclerView) findViewById(R.id.recycleView);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setNestedScrollingEnabled(false);
        int position = 1;
        sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
        loadProducts();
        listItemsArrayList = new ArrayList<>();

      /* if (listItemsArrayList.size() > 0) {
            myAdapter = new MyAdapter(listItemsArrayList, this);
            recyclerView.setAdapter(myAdapter);

        } else {
            Toast.makeText(getApplicationContext(), "No data found", Toast.LENGTH_LONG).show();
        }
*/

        final IntentIntegrator intentIntegrator = new IntentIntegrator(this);
        intentIntegrator.setBeepEnabled(true);
        intentIntegrator.setCameraId(0);
        final int finalPosition = position;
        FloatingActionButton floatingActionButton = (FloatingActionButton) findViewById(R.id.fab);
        floatingActionButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                intentIntegrator.initiateScan();


            }
        });
    }

    private void loadProducts() {
        StringRequest stringRequest = new StringRequest(Request.Method.GET, URL_PRODUCTS,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            //converting the string to json array object
                            JSONArray array = new JSONArray(response);

                            //traversing through all the object
                            for (int i = 0; i < array.length(); i++) {

                                //getting product object from json array
                                JSONObject product = array.getJSONObject(i);
                                //adding the product to product list
                                listItemsArrayList.add(new ListItem(
                                        product.getString("product_name"),
                                        product.getDouble("price")

                                ));
                            }

                            //creating adapter object and setting it to recyclerview
                            MyAdapter adapter = new MyAdapter(listItemsArrayList, MainActivity.this);
                            recyclerView.setAdapter(adapter);
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                });

        //adding our stringrequest to queue
        Volley.newRequestQueue(this).add(stringRequest);
    }


    @Override
    public void onBackPressed() {

        showAlertDialog();

    }

    private void showAlertDialog() {
        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setCancelable(false);
        builder.setTitle("Exit");
        builder.setMessage("Are you sure you want to leave?  ");
        builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                finish();

            }
        });
        builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        builder.create().show();
    }


    public static void setCameraDisplayOrientation(Activity activity, int cameraId, android.hardware.Camera camera) {
        android.hardware.Camera.CameraInfo info = new android.hardware.Camera.CameraInfo();
        android.hardware.Camera.getCameraInfo(cameraId, info);
        int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
        int degrees = 0;
        switch (rotation) {
            case Surface.ROTATION_0:
                degrees = 0;
                break;
            case Surface.ROTATION_90:
                degrees = 90;
                break;
            case Surface.ROTATION_180:
                degrees = 180;
                break;
            case Surface.ROTATION_270:
                degrees = 270;
                break;
        }

        int result;
        if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
            result = (info.orientation + degrees) % 360;
            result = (360 - result) % 360;  // compensate the mirror
        } else {  // back-facing
            result = (info.orientation - degrees + 360) % 360;
        }
        camera.setDisplayOrientation(result);
    }


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);

        if (result != null) {

            if (result.getContents() == null) {
                Toast.makeText(getApplicationContext(), "No result found", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(this, "Scanned: " + result.getContents(), Toast.LENGTH_LONG).show();
                arrayList.clear();
                myAdapter = new MyAdapter(arrayList, this);
                recyclerView.setAdapter(myAdapter);
                myAdapter.notifyDataSetChanged();
            }

        } else {
            super.onActivityResult(requestCode, resultCode, data);
        }
    }
}

我的适配器代码

Java包com.example.scan；

import android.content.Context;
import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.text.util.Linkify;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.List;

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyAdapterViewHolder> {

    List<ListItem> listItemsArrayList;
    Context context;

    public MyAdapter(List<ListItem> listItemsArrayList, Context context) {
        this.listItemsArrayList = listItemsArrayList;
        this.context = context;

    }

    @NonNull
    @Override
    public MyAdapterViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_layout, parent, false);
        return new MyAdapterViewHolder(v);

    }

    @Override
    public void onBindViewHolder(@NonNull MyAdapterViewHolder holder, int position) {
        ListItem listItem = listItemsArrayList.get(position);

        holder.textViewCode.setText(listItem.getProduct_name());
        holder.textViewType.setText(String.valueOf(listItem.getPrice()));
        Linkify.addLinks(holder.textViewCode, Linkify.ALL);

    }

    @Override
    public int getItemCount() {

        return listItemsArrayList.size();
    }

    public void removeItem(int position) {
        listItemsArrayList.remove(position);
        // notify the item removed by position
        // to perform recycler view delete animations
        // NOTE: don't call notifyDataSetChanged()
        notifyItemRemoved(position);
    }

    public void restoreItem(ListItem listItem, int position) {
        listItemsArrayList.add(position, listItem);
        // notify item added by position
        notifyItemInserted(position);
    }


    public class MyAdapterViewHolder extends RecyclerView.ViewHolder {
        TextView textViewCode, textViewType;
        CardView cardView;

        public MyAdapterViewHolder(final View itemView) {
            super(itemView);

            textViewCode = (TextView) itemView.findViewById(R.id.textViewCode);
            textViewType = (TextView) itemView.findViewById(R.id.textViewType);
            cardView = (CardView) itemView.findViewById(R.id.cardView);

            cardView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    String type = listItemsArrayList.get(getAdapterPosition()).getProduct_name();

                    Intent i = new Intent();
                    i.setAction(Intent.ACTION_SEND);
                    i.putExtra(Intent.EXTRA_TEXT, type);
                    i.setType("text/plain");
                    itemView.getContext().startActivity(i);


                }
            });
        }

    }


}

我希望 XAMPP 数据库中 product_name 和 price 的输出显示在 textviews 上。

标签： androidbarcode-scanner