Android 转换结果java.lang.NullPointerException时出错：lock==null
我是开发android应用程序的新手。我已经阅读了很多关于我所问问题的相关帖子，但是帖子中的提示或解决方案并没有解决我的问题。（寻找解决方案已经一周了，真的需要帮助才能继续我的项目）非常感谢Android 转换结果java.lang.NullPointerException时出错：lock==null,android,json,eclipse,android-asynctask,nullpointerexception,Android,Json,Eclipse,Android Asynctask,Nullpointerexception,我是开发android应用程序的新手。我已经阅读了很多关于我所问问题的相关帖子，但是帖子中的提示或解决方案并没有解决我的问题。（寻找解决方案已经一周了，真的需要帮助才能继续我的项目）非常感谢 import java.util.ArrayList; import java.util.HashMap; import java.util.List; import org.apache.http.NameValuePair; import org.apache.http.message.BasicN
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.example.aroma.slidingmenu.listener.JSONParser;
import android.app.ListFragment;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class ResultListFragment extends ListFragment {
TextView resultView;
public ResultListFragment(){}
//progress dialog
private ProgressDialog pDialog;
//creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String,String>> customerList;
//url to get the customer list
private static String url_search="http://192.168.1.3:80/test/getAllCustomers.php";
//JSON Node names
private static final String TAG_SUCCESS="success";
private static final String TAG_CUSTOMER="customers";
private static final String TAG_FNAME="FirstName";
private static final String TAG_LNAME="LastName";
private static final String TAG_AGE="Age";
private static final String TAG_MOBILE="Mobile";
//product JSONArray
JSONArray customers=null;
//search key value
public String searchKey;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_searchresult_list, container, false);
Toast.makeText(getActivity(),"Search result in listview",Toast.LENGTH_LONG).show();
Intent intent = getActivity().getIntent();
searchKey = intent.getStringExtra("message");
//Toast.makeText(getActivity(), searchKey, Toast.LENGTH_LONG).show();
//hshmap for listview
customerList= new ArrayList<HashMap<String,String>>();
//Loading customer in background thread
new LoadCustomer().execute();
return rootView;
}
@Override
public void onViewCreated (View view, Bundle savedInstanceState) {
ListView lv =getListView();
lv.setOnItemSelectedListener(new OnItemSelectedListener(){
@Override
public void onItemSelected(AdapterView<?> parent, View view,
int position, long id) {
// TODO Auto-generated method stub
String iid=((TextView)view.findViewById(R.id.FirstName)).getText().toString();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
// TODO Auto-generated method stub
}
});
}
/**
* Background Async Task to load customers by making HTTP request
* */
class LoadCustomer extends AsyncTask<String, String, String>{
/**
* Before starting background thread show progress dialog
* */
@Override
protected void onPreExecute(){
super.onPreExecute();
pDialog=new ProgressDialog(getActivity()); //pDialog=new ProgressDialog(ResultListFragment.this);
pDialog.setMessage("Loading customers. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting customers url
* **/
protected String doInBackground(String... args){
//Building Parameters
List<NameValuePair> params= new ArrayList<NameValuePair>();
//value captured from previous intent
params.add(new BasicNameValuePair("FirstName", searchKey));
//getting JSON string from url
JSONObject json = jParser.makeHttpRequest(url_search, "GET", params);
//check your log cat for JSON response
Log.d("Search customer", json.toString());
try{
//checking for SUCCESS TAG
int success=json.getInt(TAG_SUCCESS);
if(success==1){
//product found
//Getting array of products
customers=json.getJSONArray(TAG_CUSTOMER);
//looping through all products
for(int i=0;i<customers.length();i++){
JSONObject c=customers.getJSONObject(i);
//storing each json item in variable
String fname=c.getString(TAG_FNAME);
String lname=c.getString(TAG_LNAME);
String age=c.getString(TAG_AGE);
String mobile=c.getString(TAG_MOBILE);
//creating new HashMap
HashMap<String, String> map=new HashMap<String, String>();
//adding each child node to HashMap key =>value
map.put(TAG_FNAME, fname);
map.put(TAG_LNAME, lname);
map.put(TAG_AGE, age);
map.put(TAG_MOBILE, mobile);
//adding HashList to ArrayList
customerList.add(map);
}
}else{
//no customer found
//do sth
Handler handler = new Handler(getActivity().getMainLooper());
handler.post( new Runnable(){
public void run(){
Toast.makeText(getActivity(),"no customer found" ,Toast.LENGTH_LONG).show();
}
});
}
}catch (JSONException e){
e.printStackTrace();
}
//return "success";
return null;
}
/**
* After completing background task dismiss the progress dialog
* **/
protected void onPostExecute(String file_url){
//dimiss the dialog after getting the related customer
pDialog.dismiss();
getActivity().runOnUiThread(new Runnable(){
public void run(){
/**
* updating parsed JSON data into ListView
* **/
ListAdapter adapter =new SimpleAdapter(
getActivity(), customerList,
R.layout.list_item, new String[]{ TAG_FNAME, TAG_LNAME, TAG_AGE, TAG_MOBILE},
new int[]{R.id.FirstName,R.id.LastName,R.id.Age,R.id.Mobile});
//updating listview
setListAdapter(adapter);
}
});
}
}
}
尝试在创建的活动中调用asynctask
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_searchresult_list, container, false);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Toast.makeText(getActivity(),"Search result in listview",Toast.LENGTH_LONG).show();
Intent intent = getActivity().getIntent();
searchKey = intent.getStringExtra("message");
//Toast.makeText(getActivity(), searchKey, Toast.LENGTH_LONG).show();
//hshmap for listview
customerList= new ArrayList>();
//Loading customer in background thread
new LoadCustomer().execute();
}
您还可以检查为什么在ResultListFragment中的行号
136jsonnulljson=sb.toString（）您好，我试图在onActivityCreated中调用asynctask，但遇到了相同的错误。再次您好。。。呵呵。。我发现了一个问题，我不知道为什么会发生这种情况。我尝试用上面的代码在GenyMoon中调试我的应用程序，并获得了预期的输出。但当它与android设备一起使用时，缓冲区错误和解析器错误被捕获。我必须重新启动电脑，用我的设备重新运行应用程序，问题解决了。但这个问题似乎不一致。我更喜欢用真正的android设备和真正的url进行测试。对于emulator或localhost wamp mysql服务器，我也有类似的问题
02-12 17:17:50.599: E/Buffer Error(13636): Error converting result java.lang.NullPointerException: lock == null
02-12 17:17:50.599: E/JSON Parser(13636): Error parsing data org.json.JSONException: End of input at character 0 of
02-12 17:17:50.604: E/AndroidRuntime(13636): FATAL EXCEPTION: AsyncTask #4
02-12 17:17:50.604: E/AndroidRuntime(13636): java.lang.RuntimeException: An error occured while executing doInBackground()
02-12 17:17:50.604: E/AndroidRuntime(13636): at android.os.AsyncTask$3.done(AsyncTask.java:299)
02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.run(FutureTask.java:239)
02-12 17:17:50.604: E/AndroidRuntime(13636): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
02-12 17:17:50.604: E/AndroidRuntime(13636): at java.lang.Thread.run(Thread.java:838)
02-12 17:17:50.604: E/AndroidRuntime(13636): Caused by: java.lang.NullPointerException
02-12 17:17:50.604: E/AndroidRuntime(13636): at com.example.aroma.slidingmenu.ResultListFragment$LoadCustomer.doInBackground(ResultListFragment.java:136)
02-12 17:17:50.604: E/AndroidRuntime(13636): at com.example.aroma.slidingmenu.ResultListFragment$LoadCustomer.doInBackground(ResultListFragment.java:1)
02-12 17:17:50.604: E/AndroidRuntime(13636): at android.os.AsyncTask$2.call(AsyncTask.java:287)
02-12 17:17:50.604: E/AndroidRuntime(13636): at java.util.concurrent.FutureTask.run(FutureTask.java:234)
02-12 17:17:50.604: E/AndroidRuntime(13636): ... 4 more
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_searchresult_list, container, false);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Toast.makeText(getActivity(),"Search result in listview",Toast.LENGTH_LONG).show();
Intent intent = getActivity().getIntent();
searchKey = intent.getStringExtra("message");
//Toast.makeText(getActivity(), searchKey, Toast.LENGTH_LONG).show();
//hshmap for listview
customerList= new ArrayList>();
//Loading customer in background thread
new LoadCustomer().execute();
}