无法将 JSON 数据解析为 Listview

Question

我正在尝试将 SQL 数据库中的数据解析到 Listview 中。 我的 PHP 脚本正在运行，因为如果我在浏览器中运行它，我会得到内容。
如果我试图从我的 SQL 数据库中获取数据到列表视图中，我的应用程序什么也没有显示。
这是我的 MainActivity：

public class Locations extends AppCompatActivity implements AdapterView.OnItemClickListener {
ArrayList<productforloc> arrayList;
ListView lv;
private String TAG = Locations.class.getSimpleName();
private TextView addressField; //Add a new TextView to your activity_main to display the address
private LocationManager locationManager;
private String provider;
int i = 1;
private ProgressDialog pDialog;
String name;



// URL to get contacts JSON
private static String url = "Mylink";

ArrayList<HashMap<String, String>> contactList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.content_main);
    Intent i = getIntent();
    String cityname = i.getExtras().getString("cityname");
    TextView city = (TextView) findViewById(R.id.ort);
    city.setText(cityname);
    pDialog = new ProgressDialog(Locations.this);
    pDialog.setMessage("Please wait...");
    pDialog.setCancelable(true);
    pDialog.show();
    arrayList = new ArrayList<>();
    lv = (ListView) findViewById(R.id.lv);
    lv.setOnItemClickListener((AdapterView.OnItemClickListener) this);





runOnUiThread(new Runnable() {
        @Override
        public void run() {
            new ReadJSON().execute(url);
        }
    });

final ImageButton filteropen = (ImageButton) findViewById(R.id.aufklaupen);
    filteropen.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            RelativeLayout filter = (RelativeLayout) findViewById(R.id.filterloc);
            filter.setVisibility(View.VISIBLE);
            ImageButton filterclose = (ImageButton) findViewById(R.id.zuklappen);
            filterclose.setVisibility(View.VISIBLE);
            filteropen.setVisibility(View.INVISIBLE);

        }
    });
final ImageButton filterclose = (ImageButton) findViewById(R.id.zuklappen);
    filterclose.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            RelativeLayout filter = (RelativeLayout) findViewById(R.id.filterloc);
            filter.setVisibility(View.INVISIBLE);
            ImageButton filteropen = (ImageButton) findViewById(R.id.aufklaupen);
            filteropen.setVisibility(View.VISIBLE);
            filterclose.setVisibility(View.INVISIBLE);
        }
    });
}



class ReadJSON extends AsyncTask<String,Integer,String> {






    @Override
    protected String doInBackground(String... params) {
        return readURL(params[0]);
    }

    @Override
    protected void onPostExecute(String content) {

        try{
            JSONObject jo = new JSONObject(content);
            JSONArray ja = jo.getJSONArray("contacts");

            for(int i=0;i<ja.length();i++){
                JSONObject po = ja.getJSONObject(i);
                arrayList.add(new productforloc(
                        po.getString("imageurl"),
                        po.getString("name"),
                        po.getString("street"),
                        po.getString("postalcode"),
                        po.getString("musicstyle"),
                        po.getString("musicsecond"),
                        po.getString("entry"),
                        po.getString("opening"),
                        po.getString("agegroup"),
                        po.getString("urlbtn"),
                        po.getString("Fsk"),
                        po.getString("city"),
                        po.getString("bg")

                ));

            }



        } catch (JSONException e) {
            e.printStackTrace();
        }
        final CustomListAdapterforloc adapter = new CustomListAdapterforloc(getApplicationContext(),R.layout.model,arrayList);

        lv.setAdapter(adapter);
        if(pDialog.isShowing()){
            pDialog.dismiss();
        }
        }

    }




private String readURL(String url){
    StringBuilder content = new StringBuilder();


   try{
        URL uri = new URL(url);
        URLConnection urlConnection = uri.openConnection();
        BufferedReader bufferedReader= new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
        String line;
        while((line = bufferedReader.readLine()) !=null){
            content.append(line+"\n");


        }
        bufferedReader.close();
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return content.toString();
}

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

    productforloc pForloc = arrayList.get(position);

    Intent intent = new Intent();
    intent.setClass(this,DetailActivity.class);

    intent.putExtra("name",pForloc.getName());
    intent.putExtra("imageurl",pForloc.getImage());
    intent.putExtra("street",pForloc.getStreet());
    intent.putExtra("postalcode",pForloc.getPostalcode());
    intent.putExtra("entry",pForloc.getEntry());
    intent.putExtra("agegroup",pForloc.getAgegroup());
    intent.putExtra("opening",pForloc.getOpening());
    intent.putExtra("urlbtn",pForloc.getUrlbtn());
    intent.putExtra("Fsk",pForloc.getFsk());
    intent.putExtra("city",pForloc.getCity());
    intent.putExtra("musicstyle",pForloc.getMusicstyle());
    intent.putExtra("musicsecond",pForloc.getMusicsecond());
    intent.putExtra("bg",pForloc.getBg());
    startActivity(intent);


}

/**
 * Async task class to get json by making HTTP call

 }



 */

}

这是我的 Customlistadapter 活动：

public class CustomListAdapterforloc extends ArrayAdapter<productforloc>{

ArrayList<productforloc> products;
Context context;
int resource;
public CustomListAdapterforloc(Context context, int resource, List<productforloc> products) {

    super(context, resource, products);
    this.products = (ArrayList<productforloc>) products;
    this.context = context;
    this.resource = resource;
}

@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {

    if(convertView== null){
        LayoutInflater layoutInflater = (LayoutInflater) getContext().getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        convertView = layoutInflater.inflate(R.layout.model,null,true);
    }
    productforloc product = getItem(position);

    ImageView imageView = (ImageView) convertView.findViewById(R.id.imagelist);
    Picasso.with(context).load(product.getImage()).into(imageView);
    TextView txtName= (TextView) convertView.findViewById(R.id.namelist);
    txtName.setText(product.getName());



    return convertView;

}

}

Answer 1

我在我的 MAinActivity 中使用此代码解决了它：

public class Locations extends AppCompatActivity {
private String TAG = Locations.class.getSimpleName();

private ProgressDialog pDialog;
private ListView lv;

// URL to get contacts JSON
private static String url = "http://partypeople.bplaced.net/loli.php";

ArrayList<HashMap<String, String>> contactList;

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

    contactList = new ArrayList<>();

    lv = (ListView) findViewById(R.id.lv);

    new GetContacts().execute();
}

/**
 * Async task class to get json by making HTTP call
 */
private class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(Locations.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();

    }

    @Override
    protected Void doInBackground(Void... arg0) {
        HttpHandler sh = new HttpHandler();

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(url);

        Log.e(TAG, "Response from url: " + jsonStr);

        if (jsonStr != null) {
            try {
                JSONArray contacts = new JSONArray(jsonStr);

                // Getting JSON Array node


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

                    String id = c.getString("id");
                    String name = c.getString("name");
                    String email = c.getString("email");
                    String address = c.getString("address");
                    String gender = c.getString("gender");



                    // tmp hash map for single contact
                    HashMap<String, String> contact = new HashMap<>();

                    // adding each child node to HashMap key => value
                    contact.put("id", id);
                    contact.put("name", name);
                    contact.put("email", email);


                    // adding contact to contact list
                    contactList.add(contact);
                }
            } catch (final JSONException e) {
                Log.e(TAG, "Json parsing error: " + e.getMessage());
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Json parsing error: " + e.getMessage(),
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }
        } else {
            Log.e(TAG, "Couldn't get json from server.");
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(),
                            "Couldn't get json from server. Check LogCat for possible errors!",
                            Toast.LENGTH_LONG)
                            .show();
                }
            });

        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        // Dismiss the progress dialog
        if (pDialog.isShowing())
            pDialog.dismiss();
        /**3
         * Updating parsed JSON data into ListView
         * */
        ListAdapter adapter = new SimpleAdapter(
                Locations.this, contactList,
                R.layout.model, new String[]{"name", "email",
                "mobile"}, new int[]{R.id.namelist,
               });

        lv.setAdapter(adapter);
    }

}

并在我的 CustomlistadapterActivity 中使用：

public class HttpHandler {


private static final String TAG = HttpHandler.class.getSimpleName();

public HttpHandler() {
}

public String makeServiceCall(String reqUrl) {
    String response = null;
    try {
        URL url = new URL(reqUrl);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        // read the response
        InputStream in = new BufferedInputStream(conn.getInputStream());
        response = convertStreamToString(in);
    } catch (MalformedURLException e) {
        Log.e(TAG, "MalformedURLException: " + e.getMessage());
    } catch (ProtocolException e) {
        Log.e(TAG, "ProtocolException: " + e.getMessage());
    } catch (IOException e) {
        Log.e(TAG, "IOException: " + e.getMessage());
    } catch (Exception e) {
        Log.e(TAG, "Exception: " + e.getMessage());
    }
    return response;
}

private String convertStreamToString(InputStream is) {
    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder sb = new StringBuilder();

    String line;
    try {
        while ((line = reader.readLine()) != null) {
            sb.append(line).append('\n');
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return sb.toString();
}

}

感谢您的意见

Answer 2

将 getCount 方法覆盖到适配器类中。