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私はphpサーバからの食品情報リストを表示するリストビューを設計しています。 私が渡したURLはjsonファイルに変換した後のPHPファイルです。リストが示され、whent私は（アプリは動作を停止） を得続けるメニューからリフレッシュを押していません。..カスタムlistViewアダプタ、モデル、JSONParsingが機能しない
ここFoodView.java活動
あるimport android.content.Context;
import android.os.AsyncTask;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.w3c.dom.Text;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;
import alsaad.layla.mysqldemo.Models.FoodModel;
import static android.R.attr.resource;
import static android.content.Context.LAYOUT_INFLATER_SERVICE;
public class FoodView extends AppCompatActivity {
private ListView lvFood;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_food_view);
lvFood = (ListView) findViewById(R.id.lvFood);
}
public class JSONTask extends AsyncTask<String, String, List<FoodModel>> {
@Override
protected List<FoodModel> doInBackground(String... params) {
HttpURLConnection httpURLConnection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.connect();
InputStream inputStream = httpURLConnection.getInputStream();
reader = new BufferedReader(new InputStreamReader(inputStream));
StringBuffer buffer = new StringBuffer();
String line = "";
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
String finalJson = buffer.toString();
JSONArray parentArray = new JSONArray(finalJson);
List<FoodModel> foodModelList = new ArrayList<>();
for (int i = 0; i < parentArray.length(); i++) {
JSONObject finalObject = parentArray.getJSONObject(i);
FoodModel foodModel = new FoodModel();
foodModel.setFood(finalObject.getString("name"));
//foodModel.setStatus(finalObject.getString("status"));
foodModel.setAmount(finalObject.getInt("amount"));
foodModel.setDescription(finalObject.getString("description"));
foodModel.setDate(finalObject.getInt("exDate"));
foodModelList.add(foodModel);
}
return foodModelList;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} finally {
if (httpURLConnection != null) {
httpURLConnection.disconnect();
}
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(List<FoodModel> result) {
super.onPostExecute(result);
FoodAdapter adapter = new FoodAdapter(getApplicationContext(), R.layout.row, result);
lvFood.setAdapter(adapter);
}}
public class FoodAdapter extends ArrayAdapter {
private List<FoodModel> foodModelList;
private int resource;
private LayoutInflater inflater;
public FoodAdapter(Context context, int resource, List<FoodModel> objects) {
super(context, resource, objects);
foodModelList = objects;
this.resource = resource;
inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = inflater.inflate(resource, null);
}
ImageView ivIcon;
TextView foodName, txt_amount, txt_desc, txt_date, txt_status;
ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);
foodName = (TextView) convertView.findViewById(R.id.foodName);
txt_amount = (TextView) convertView.findViewById(R.id.txt_amount);
txt_desc = (TextView) convertView.findViewById(R.id.txt_desc);
// txt_status = (TextView) convertView.findViewById(R.id.txt_status);
txt_date = (TextView) convertView.findViewById(R.id.txt_date);
foodName.setText(foodModelList.get(position).getFood());
txt_amount.setText("Amount: " + foodModelList.get(position).getAmount());
txt_desc.setText(foodModelList.get(position).getDescription());
// txt_status.setText(foodModelList.get(position).getStatus());
txt_date.setText("Date: " + foodModelList.get(position).getDate());
return convertView;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.navigation_drawer, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_refresh) {
new JSONTask().execute("http://10.0.3.2/MySqlDemo/food.php");
return true;
}
return super.onOptionsItemSelected(item);
}
}
FoodModel.java
public class FoodModel {
private String food;
//private enum status;
private int amount;
private String image;
private String description;
private int date;
public int getDate() {
return date;
}
public void setDate(int date) {
this.date = date;
}
public String getFood() {
return food;
}
public void setFood(String food) {
this.food = food;
}
//public String getStatus() {
// return status;
// }
// public void setStatus(String status) {
// this.status = status;
//}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public int getAmount() {
return amount;
}
public void setAmount(int amount) {
this.amount = amount;
}
}
logcatエラー：
02-20 05:06:08.084 4514-4514/alsaad.layla.mysqldemo E/AndroidRuntime: FATAL EXCEPTION: main java.lang.NullPointerException at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:330) at android.widget.ListView.setAdapter(ListView.java:462) at alsaad.layla.mysqldemo.FoodView$JSONTask.onPostExecute(FoodView.java:128) at alsaad.layla.mysqldemo.FoodView$JSONTask.onPostExecute(FoodView.java:54) at android.os.AsyncTask.finish(AsyncTask.java:631) at android.os.AsyncTask.access$600(AsyncTask.java:177) at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:5041) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) at dalvik.system.NativeStart.main(Native Method)
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