Android Studio ListViewAdapter错误
请帮我解决这个问题..
我将之前的问题改为此..
我无法发布新问题，因为我有被封锁的危险..
继承人我的问题..
我试图从数据库中获取数据，但是当我运行应用程序时出现此错误..
09-29 13:41:07.032 26507-26507/? E/Error﹕ No value for result
09-29 13:41:07.032 26507-26507/? W/System.err﹕ org.json.JSONException: No value for result
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at org.json.JSONObject.get(JSONObject.java:354)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at org.json.JSONObject.getJSONArray(JSONObject.java:548)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at com.example.administrator.mosbeau.CategoryFragment.prepareListData(CategoryFragment.java:249)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at com.example.administrator.mosbeau.CategoryFragment$1GetDataJSON.onPostExecute(CategoryFragment.java:233)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at com.example.administrator.mosbeau.CategoryFragment$1GetDataJSON.onPostExecute(CategoryFragment.java:180)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at android.os.AsyncTask.finish(AsyncTask.java:631)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at android.os.AsyncTask.access$600(AsyncTask.java:177)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:99)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at android.os.Looper.loop(Looper.java:137)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5494)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:525)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:875)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:691)
09-29 13:41:07.032 26507-26507/? W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
09-29 13:41:07.042 26507-26507/? I/MemoryCache﹕ MemoryCache will use up to 24.0MB
09-29 13:41:07.042 26507-26507/? D/AndroidRuntime﹕ Shutting down VM
09-29 13:41:07.042 26507-26507/? W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418e38e0)
09-29 13:41:07.042 26507-26507/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.administrator.mosbeau.ListViewAdapter.getCount(ListViewAdapter.java:38)
at android.widget.ListView.setAdapter(ListView.java:463)
at com.example.administrator.mosbeau.CategoryFragment$1GetDataJSON.onPostExecute(CategoryFragment.java:236)
at com.example.administrator.mosbeau.CategoryFragment$1GetDataJSON.onPostExecute(CategoryFragment.java:180)
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:5494)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:875)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:691)
at dalvik.system.NativeStart.main(Native Method)
09-29 13:41:07.052 941-7799/? I/ActivityManager﹕ Notify an ApplicationCrash
这是代码..
CategoryFragment.java
package com.example.administrator.mosbeau;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.ExpandableListView;
import android.widget.ListView;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
/**
* Created by Administrator on 9/18/2015.
*/
public class CategoryFragment extends Fragment {
public static CategoryFragment newInstance(String id,String name) {
CategoryFragment fragment = new CategoryFragment();
Bundle bundle = new Bundle();
bundle.putString("id", id);
bundle.putString("name", name);
fragment.setArguments(bundle);
return fragment;
}
public CategoryFragment () {
}
EditText tpid, tpname;
String cid;
String cname;
String myJSON;
JSONObject jsonobject;
JSONArray jsonarray;
ListView productlistview;
ListViewAdapter adapter;
ProgressDialog mProgressDialog;
ArrayList<HashMap<String, String>> arraylist;
static final String result="result";
static String products_id = "products_id";
static String products_name = "products_name";
static String products_price = "products_price";
static String products_image = "products_image";
Boolean InternetAvailable = false;
Seocnd detectconnection;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View rootView = inflater.inflate(R.layout.categorylayout, container, false);
getActivity().invalidateOptionsMenu();
tpid = (EditText) rootView.findViewById(R.id.tpid);
tpname = (EditText) rootView.findViewById(R.id.tpname);
if(getArguments() != null) {
String catid = getArguments().getString("id");
String catname = getArguments().getString("name");
tpid.setText(catid);
tpname.setText(catname);
cid = catid;
cname = catname;
}
productlistview = (ListView) rootView.findViewById(R.id.productlistview);
//new DownloadJSON().execute();
detectconnection = new Seocnd(getActivity());
InternetAvailable = detectconnection.InternetConnecting();
if (InternetAvailable) {
getProduct();
} else {
NointernetFragment fragment = new NointernetFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container, fragment)
.commit();
}
return rootView;
}
public void getProduct(){
class GetDataJSON extends AsyncTask<String, Void, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Create a progressdialog
mProgressDialog = new ProgressDialog(getActivity());
// Set progressdialog title
mProgressDialog.setTitle(cname);
// Set progressdialog message
mProgressDialog.setMessage("Loading...");
mProgressDialog.setIndeterminate(false);
// Show progressdialog
mProgressDialog.show();
}
@Override
protected String doInBackground(String... params) {
DefaultHttpClient httpclient = new DefaultHttpClient(new BasicHttpParams());
HttpPost httppost = new HttpPost("http://joehamirbalabadan.com/android/android/products.php");
// Depends on your web service
httppost.setHeader("Content-type", "application/json");
InputStream inputStream = null;
String result = null;
try {
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
inputStream = entity.getContent();
// json is UTF-8 by default
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null)
{
sb.append(line + "\n");
}
result = sb.toString();
} catch (Exception e) {
// Oops
}
finally {
try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
}
return result;
}
@Override
protected void onPostExecute(String result){
myJSON=result;
prepareListData();
adapter = new ListViewAdapter(getActivity(), arraylist);
// Set the adapter to the ListView
productlistview.setAdapter(adapter);
// Close the progressdialog
mProgressDialog.dismiss();
}
}
GetDataJSON g = new GetDataJSON();
g.execute();
}
protected void prepareListData(){
try {
// Locate the array name in JSON
JSONObject jsonObj = new JSONObject(myJSON);
jsonarray = jsonObj.getJSONArray(result);
HashMap<String, String> map = new HashMap<String, String>();
for (int i = 0; i < jsonarray.length(); i++) {
JSONObject p = jsonarray.getJSONObject(i);
// Retrive JSON Objects
map.put("products_id", p.getString("products_id"));
map.put("products_name", p.getString("products_name"));
map.put("products_price", p.getString("products_price"));
map.put("products_image", p.getString("products_image"));
// Set the JSON Objects into the array
arraylist.add(map);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(2);
}
}
ListViewAdapter.java
package com.example.administrator.mosbeau;
/**
* Created by Administrator on 9/28/2015.
*/
import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.HashMap;
public class ListViewAdapter extends BaseAdapter {
// Declare Variables
Context context;
LayoutInflater inflater;
ArrayList<HashMap<String, String>> data;
ImageLoader imageLoader;
HashMap<String, String> resultp = new HashMap<String, String>();
public ListViewAdapter(Context context,
ArrayList<HashMap<String, String>> arraylist) {
this.context = context;
data = arraylist;
imageLoader = new ImageLoader(context);
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
public View getView(final int position, View convertView, ViewGroup parent) {
// Declare Variables
TextView products_id;
TextView products_name;
TextView products_price;
ImageView products_image;
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View itemView = inflater.inflate(R.layout.product_listview_item, parent, false);
// Get the position
resultp = data.get(position);
// Locate the TextViews in product_listview_item.xml
products_id = (TextView) itemView.findViewById(R.id.products_id);
products_name = (TextView) itemView.findViewById(R.id.products_name);
products_price = (TextView) itemView.findViewById(R.id.products_price);
// Locate the ImageView in product_listview_item.xml
products_image = (ImageView) itemView.findViewById(R.id.products_image);
// Capture position and set results to the TextViews
products_id.setText(resultp.get(CategoryFragment.products_id));
products_name.setText(resultp.get(CategoryFragment.products_name));
products_price.setText(resultp.get(CategoryFragment.products_price));
// Capture position and set results to the ImageView
// Passes flag images URL into ImageLoader.class
imageLoader.DisplayImage(resultp.get(CategoryFragment.products_image), products_image);
// Capture ListView item click
itemView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// Get the position
resultp = data.get(position);
Intent intent = new Intent(context, SingleItemView.class);
// Pass all data rank
intent.putExtra("products_id", resultp.get(CategoryFragment.products_id));
// Pass all data country
intent.putExtra("products_name", resultp.get(CategoryFragment.products_name));
// Pass all data population
intent.putExtra("products_price",resultp.get(CategoryFragment.products_price));
// Pass all data flag
intent.putExtra("products_image", resultp.get(CategoryFragment.products_image));
// Start SingleItemView Class
context.startActivity(intent);
}
});
return itemView;
}
}
新错误
09-29 14:12:26.981 593-593/? W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x409bf1f8)
09-29 14:12:26.992 593-593/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.administrator.mosbeau.CategoryFragment.prepareListData(CategoryFragment.java:259)
at com.example.administrator.mosbeau.CategoryFragment$1GetDataJSON.onPostExecute(CategoryFragment.java:232)
at com.example.administrator.mosbeau.CategoryFragment$1GetDataJSON.onPostExecute(CategoryFragment.java:179)
at android.os.AsyncTask.finish(AsyncTask.java:602)
at android.os.AsyncTask.access$600(AsyncTask.java:156)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
这是第259行
arraylist.add(map);
第232行
prepareListData();
更新代码
CategoryFragment.java
package com.example.administrator.mosbeau;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.ExpandableListView;
import android.widget.ListView;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
/**
* Created by Administrator on 9/18/2015.
*/
public class CategoryFragment extends Fragment {
public static CategoryFragment newInstance(String id,String name) {
CategoryFragment fragment = new CategoryFragment();
Bundle bundle = new Bundle();
bundle.putString("id", id);
bundle.putString("name", name);
fragment.setArguments(bundle);
return fragment;
}
public CategoryFragment () {
}
EditText tpid, tpname;
String cid;
String cname;
String myJSON;
JSONObject jsonobject;
JSONArray jsonarray;
ListView productlistview;
ListViewAdapter adapter;
ProgressDialog mProgressDialog;
ArrayList<HashMap<String, String>> arraylist;
public static String products_id = "products_id";
public static String products_name = "products_name";
public static String products_price = "products_price";
public static String products_image = "products_image";
Boolean InternetAvailable = false;
Seocnd detectconnection;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View rootView = inflater.inflate(R.layout.categorylayout, container, false);
getActivity().invalidateOptionsMenu();
tpid = (EditText) rootView.findViewById(R.id.tpid);
tpname = (EditText) rootView.findViewById(R.id.tpname);
if(getArguments() != null) {
String catid = getArguments().getString("id");
String catname = getArguments().getString("name");
tpid.setText(catid);
tpname.setText(catname);
cid = catid;
cname = catname;
}
productlistview = (ListView) rootView.findViewById(R.id.productlistview);
//new DownloadJSON().execute();
detectconnection = new Seocnd(getActivity());
InternetAvailable = detectconnection.InternetConnecting();
if (InternetAvailable) {
getProduct();
} else {
NointernetFragment fragment = new NointernetFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container, fragment)
.commit();
}
return rootView;
}
public void getProduct(){
class DownloadJSON extends AsyncTask<String, Void, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Create a progressdialog
mProgressDialog = new ProgressDialog(getActivity());
// Set progressdialog title
mProgressDialog.setTitle(cname);
// Set progressdialog message
mProgressDialog.setMessage("Loading...");
mProgressDialog.setIndeterminate(false);
// Show progressdialog
mProgressDialog.show();
}
@Override
protected String doInBackground(String... params) {
DefaultHttpClient httpclient = new DefaultHttpClient(new BasicHttpParams());
HttpPost httppost = new HttpPost("http://joehamirbalabadan.com/android/android/products.php");
// Depends on your web service
httppost.setHeader("Content-type", "application/json");
InputStream inputStream = null;
String result = null;
try {
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
inputStream = entity.getContent();
// json is UTF-8 by default
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null)
{
sb.append(line + "\n");
}
result = sb.toString();
} catch (Exception e) {
// Oops
}
finally {
try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
}
return result;
}
@Override
protected void onPostExecute(String result){
myJSON=result;
try {
// Locate the array name in JSON
JSONObject jsonObj = new JSONObject(myJSON);
jsonarray = jsonObj.getJSONArray("products");
arraylist = new ArrayList<HashMap<String, String>>();
for (int i = 0; i < jsonarray.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
JSONObject p = jsonarray.getJSONObject(i);
// Retrive JSON Objects
map.put("products_id", p.getString("products_id"));
map.put("products_name", p.getString("products_name"));
map.put("products_price", p.getString("products_price"));
map.put("products_image", p.getString("products_image"));
// Set the JSON Objects into the array
arraylist.add(map);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
adapter = new ListViewAdapter(getActivity(), arraylist);
// Set the adapter to the ListView
productlistview.setAdapter(adapter);
// Close the progressdialog
mProgressDialog.dismiss();
}
}
DownloadJSON g = new DownloadJSON();
g.execute();
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(2);
}
}
当我在此代码中使用.php文件时，图像不显示..
DefaultHttpClient httpclient = new DefaultHttpClient(new BasicHttpParams());
HttpPost httppost = new HttpPost("http://joehamirbalabadan.com/android/android/products.php");
但是当我使用.txt文件时，它可以工作..
我尝试复制products.php的数据并将其另存为.txt然后我将链接更改为此http://joehamirbalabadan.com/android/android/products.txt ..
它的工作..但我想使用.php文件，因为我用它来从数据库中获取数据..
products.php结果
products.txt结果
请帮帮我..
3 个答案:
答案 0 :(得分：2)
首先尝试初始化arraylist并在for循环中创建HashMap项新实例，如：
protected void prepareListData(){
try {
arraylist = new ArrayList<HashMap<String, String>>();
// Locate the array name in JSON
JSONObject jsonObj = new JSONObject(myJSON);
jsonarray = jsonObj.getJSONArray(result);
for (int i = 0; i < jsonarray.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
JSONObject p = jsonarray.getJSONObject(i);
// Retrive JSON Objects
map.put("products_id", p.getString("products_id"));
map.put("products_name", p.getString("products_name"));
map.put("products_price", p.getString("products_price"));
map.put("products_image", p.getString("products_image"));
// Set the JSON Objects into the array
arraylist.add(map);
}
catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
}
答案 1 :(得分：1)
使用以下产品初始化结果字符串：
static final String result="products";
它会起作用
答案 2 :(得分：0)
我认为你需要在变量之下进行十分转换
static final String result="result";
static String products_id = "products_id";
static String products_name = "products_name";
static String products_price = "products_price";
static String products_image = "products_image";
你必须像这样改变
public static final String result="result";
public static String products_id = "products_id";
public static String products_name = "products_name";
public static String products_price = "products_price";
public static String products_image = "products_image";
我希望它有效。
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