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我正在开发一个新闻Android应用程序，填写列表视图时，我有以下代码充满文字和图片来自在线服务器列表视图：奇怪的空指针异常从在线数据库
package info.androidhive.actionbar;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.HashMap;
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.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.annotation.TargetApi;
import android.app.ActionBar;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.app.SearchManager;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.StrictMode;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.style.ImageSpan;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class News extends ListActivity implements
ActionBar.OnNavigationListener {
private ProgressDialog pd;
Handler handler;
ArrayList<NameValuePair> nameValuePairs;
HttpResponse response;
HttpEntity entity;
HttpClient httpclient;
String wholepost="";
// CustomAdapter adapter;
HttpPost httppost;
TextView scrolltext;
//String date,content,sender1,sender2,mid,nc;
CategoryAdapter adapter;
String type,username,title,nc,content,date,time,internet="yes";
private ListView listView1;
private String titlearray[];
private String contentarray[];
private String datearray[];
private String task_type[];
private String deleted_task[];
private String task_id[];
String[] postsinarray;
String[] arrayinlist;
JSONArray arr;
Bitmap[] bit=null;
//String type;
private ActionBar actionBar;
// Refresh menu item
private MenuItem refreshMenuItem;
ArrayList<HashMap<String, Object>> searchResults;
ArrayList<HashMap<String, Object>> originalValues;
LayoutInflater inflater;
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// final ListView playerListView=(ListView) findViewById(android.R.id.list);
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);
forceRTLIfSupported();
actionBar = getActionBar();
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle("أخبار الساعة");
scrolltext=(TextView) findViewById(R.id.textView1);
scrolltext.setText("");
scrolltext.setTextColor(Color.BLACK);
pd=new ProgressDialog(News.this,R.style.TransparentProgressDialog);
pd.setProgressStyle(ProgressDialog.STYLE_SPINNER);
pd.setMessage("جار تحميل الأخبار");
pd.setCancelable(false);
pd.setIndeterminate(true);
handler=new Handler();
inflater=(LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
///////////////////////////////////////////////////////////////////////
ConnectivityManager cm =(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnectedOrConnecting())
{
// new ProgressTask().execute();
/////////////////////////////////////////////////////////////////////////////////////////////////////////////
pd.show();
Thread thread = new Thread() {
public void run() {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
//httpclient = new DefaultHttpClient();
httpclient = new DefaultHttpClient();
String type2="moonwalker";
httppost = new HttpPost("http://www.mypage.com/myfolder/mypage.php?Username="+type2+"");
try
{
nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("Type",type));
nameValuePairs.add(new BasicNameValuePair("Date",date));
nameValuePairs.add(new BasicNameValuePair("Title",title));
nameValuePairs.add(new BasicNameValuePair("Content",content));
nameValuePairs.add(new BasicNameValuePair("Time",time));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs,"UTF-8"));
response = httpclient.execute(httppost);
if(response.getStatusLine().getStatusCode()==200)
{
entity=response.getEntity();
if(entity !=null)
{
InputStream instream=entity.getContent();
try {
JSONArray jArray = new JSONArray(convertStreamToString(instream));
arr=jArray;
// int jArrayLength = arr.length();
postsinarray = new String[arr.length()];
arrayinlist=new String[arr.length()];
//final List<String> listContents = new ArrayList<String>(jArrayLength);
//thelist=listContents;
Category task_data[] = new Category[arr.length()];
titlearray=new String[arr.length()];
contentarray=new String[arr.length()];
datearray=new String[arr.length()];
task_type=new String[arr.length()];
task_id=new String[arr.length()];
deleted_task=new String[arr.length()];
for(int i =0; i<arr.length(); i++){
try
{
JSONObject json_data = arr.getJSONObject(i);
// String postcontent=new String(json_data.getString("Content").getBytes("ISO-8859-1"), "UTF-8");
// String TAG_ID = null;
String postcontent=URLDecoder.decode(json_data.getString("Content"), "UTF-8");
wholepost= wholepost+postcontent+"\t\t\t\t";
contentarray[i]=postcontent;
if(postcontent.length()>64)
{
String subpost=postcontent.substring(0,50);
String newcontent=subpost+"...";
nc=newcontent;
}
else
{
nc=postcontent;
}
String posttype=json_data.getString("Type");
task_type[i]=posttype;
StrictMode.ThreadPolicy policy1= new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
URL newurl = new URL("http://mypage.com/myfolder/photos/mini_"+posttype+".jpg");
Bitmap mIcon_val = BitmapFactory.decodeStream(newurl.openConnection() .getInputStream());
task_data[i]=new Category(mIcon_val, json_data.getString("Title"),nc,json_data.getString("Date"),json_data.getString("Taskid"));
titlearray[i]=json_data.getString("Title");
datearray[i]=json_data.getString("Date");
task_id[i]=json_data.getString("Taskid");
adapter = new CategoryAdapter(News.this, R.layout.list_row, task_data);
//listcount=listView1.getCount();
}catch(Exception ex){Toast.makeText(getBaseContext(), ex.toString(), Toast.LENGTH_LONG).show();}
}
pd.dismiss();
}catch(JSONException e){
}}}
}//End of first try
catch(Exception e)
{
// Toast.makeText(getBaseContext(),"CONNECTION ERROR",Toast.LENGTH_LONG).show();
}
handler.post(new Runnable() {
@Override
public void run() {
listView1 = (ListView)findViewById(android.R.id.list);
listView1.setAdapter(adapter);
adapter.notifyDataSetChanged();
SpannableString ss = new SpannableString("\t\t\t\t"+wholepost);
Drawable d = getResources().getDrawable(R.drawable.mini_globe);
d.setBounds(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
ImageSpan span = new ImageSpan(d, ImageSpan.ALIGN_BASELINE);
ss.setSpan(span, 0, 3, Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
scrolltext.setText(ss);
pd.dismiss();
}
});
}
};
thread.start();
///////////////////////////////////////////////////////////////////////////////////////////////////////////
// End of first catch
}
else
{
Toast.makeText(getBaseContext(),"No internet connection", Toast.LENGTH_LONG).show();
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
listView1 = (ListView)findViewById(android.R.id.list);
listView1.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
// TODO Auto-generated method stub
ConnectivityManager cm =(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnectedOrConnecting())
{
String postcontent=contentarray[arg2];
String posttitle=titlearray[arg2];
String postphoto=task_type[arg2];
Intent intent = new Intent(News.this, Postcontent.class);
// 2. put key/value data
intent.putExtra("message", "Hello From MainActivity");
// 3. or you can add data to a bundle
Bundle extras = new Bundle();
extras.putString("title",posttitle);
extras.putString("content",postcontent);
extras.putString("photo",postphoto);
// 4. add bundle to intent
intent.putExtras(extras);
// 5. start the activity
startActivity(intent);
}
else
{
Toast.makeText(getBaseContext(),"No internet connection", Toast.LENGTH_LONG).show();
}
}
});
}
//define your custom adapter
private static String convertStreamToString(InputStream is)
{
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try
{
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
}catch(IOException e)
{
}
finally
{
try{
is.close();
}catch(IOException e)
{
}
}return sb.toString();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.activity_main_actions, menu);
return super.onCreateOptionsMenu(menu);
}
/**
* On selecting action bar icons
* */
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Take appropriate action for each action item click
switch (item.getItemId()) {
case R.id.action_refresh:
// refresh
refreshMenuItem = item;
new ProgressTask().execute();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/**
* Launching new activity
* */
/*
* Actionbar navigation item select listener
*/
@Override
public boolean onNavigationItemSelected(int itemPosition, long itemId) {
// Action to be taken after selecting a spinner item
return false;
}
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
private void forceRTLIfSupported()
{
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1){
getWindow().getDecorView().setLayoutDirection(View.LAYOUT_DIRECTION_RTL);
}
}
protected void onPostExecute(Object result) {
try {
if ((this.pd != null) && this.pd.isShowing()) {
this.pd.dismiss();
}
} catch (final IllegalArgumentException e) {
// Handle or log or ignore
} catch (final Exception e) {
// Handle or log or ignore
} finally {
this.pd = null;
}
}
private class ProgressTask extends AsyncTask <Void,Void,Void>
{
@Override
protected void onPreExecute()
{
refreshMenuItem.setActionView(R.layout.action_progressbar);
refreshMenuItem.expandActionView();
}
@Override
protected Void doInBackground(Void... params)
{
ConnectivityManager cm =(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnectedOrConnecting())
{
internet="yes";
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
//httpclient = new DefaultHttpClient();
httpclient = new DefaultHttpClient();
String type2="moonwalker";
httppost = new HttpPost("http://mypage.com/myfolder/mypage.php?Username="+type2+"");
try
{
nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("Type",type));
nameValuePairs.add(new BasicNameValuePair("Date",date));
nameValuePairs.add(new BasicNameValuePair("Title",title));
nameValuePairs.add(new BasicNameValuePair("Content",content));
nameValuePairs.add(new BasicNameValuePair("Time",time));
//
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs,"UTF-8"));
response = httpclient.execute(httppost);
//
//
//
if(response.getStatusLine().getStatusCode()==200)
{
//
entity=response.getEntity();
if(entity !=null)
{
InputStream instream=entity.getContent();
try {
JSONArray jArray = new JSONArray(convertStreamToString(instream));
arr=jArray;
// int jArrayLength = arr.length();
postsinarray = new String[arr.length()];
arrayinlist=new String[arr.length()];
}catch(JSONException e){
//
}}}
}//End of first try
//
catch(Exception e)
{
}
//
Category task_data[] = new Category[arr.length()];
titlearray=new String[arr.length()];
contentarray=new String[arr.length()];
datearray=new String[arr.length()];
task_type=new String[arr.length()];
task_id=new String[arr.length()];
deleted_task=new String[arr.length()];
//
for(int i =0; i<arr.length(); i++){
try
{
JSONObject json_data = arr.getJSONObject(i);
String postcontent=URLDecoder.decode(json_data.getString("Content"), "UTF-8");
wholepost= wholepost+postcontent+"\t\t\t\t";
contentarray[i]=postcontent;
//
if(postcontent.length()>64)
{
String subpost=postcontent.substring(0,50);
String newcontent=subpost+"...";
nc=newcontent;
}
else
{
nc=postcontent;
}
String posttype=json_data.getString("Type");
task_type[i]=posttype;
StrictMode.ThreadPolicy policy2 = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
//
URL newurl = new URL("http://mypage.com/myfolder/photos/mini_"+posttype+".jpg");
Bitmap mIcon_val = BitmapFactory.decodeStream(newurl.openConnection() .getInputStream());
task_data[i]=new Category(mIcon_val, json_data.getString("Title"),nc,json_data.getString("Date"),json_data.getString("Taskid"));
titlearray[i]=json_data.getString("Title");
datearray[i]=json_data.getString("Date");
task_id[i]=json_data.getString("Taskid");
adapter = new CategoryAdapter(News.this, R.layout.list_row, task_data);
//
}
catch(Exception ex)
{
Toast.makeText(getBaseContext(), ex.toString(), Toast.LENGTH_LONG).show();
}
}
}
else
{internet="non";
//Toast.makeText(getBaseContext(),"No internet connection", Toast.LENGTH_LONG).show();
}
return null;
}
@Override
protected void onPostExecute(Void result)
{
if(internet.equals("yes"))
{
listView1 = (ListView)findViewById(android.R.id.list);
listView1.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
else
{
Toast.makeText(getBaseContext(),"No internet connection", Toast.LENGTH_LONG).show();
}
// scrolltext.setText(wholepost);
refreshMenuItem.collapseActionView();
// remove the progress bar view
refreshMenuItem.setActionView(null);
//Toast.makeText(getBaseContext(),message, Toast.LENGTH_LONG).show();
}
}
}
如果我打开拳头时间的应用程序，它崩溃，并给了我以下错误：
10-28 09:09:28.680: E/AndroidRuntime(2840): FATAL EXCEPTION: main
10-28 09:09:28.680: E/AndroidRuntime(2840): java.lang.NullPointerException
10-28 09:09:28.680: E/AndroidRuntime(2840): at info.androidhive.actionbar.News$1$1.run(News.java:283)
10-28 09:09:28.680: E/AndroidRuntime(2840): at android.os.Handler.handleCallback(Handler.java:725)
10-28 09:09:28.680: E/AndroidRuntime(2840): at android.os.Handler.dispatchMessage(Handler.java:92)
10-28 09:09:28.680: E/AndroidRuntime(2840): at android.os.Looper.loop(Looper.java:137)
10-28 09:09:28.680: E/AndroidRuntime(2840): at android.app.ActivityThread.main(ActivityThread.java:5041)
10-28 09:09:28.680: E/AndroidRuntime(2840): at java.lang.reflect.Method.invokeNative(Native Method)
10-28 09:09:28.680: E/AndroidRuntime(2840): at java.lang.reflect.Method.invoke(Method.java:511)
10-28 09:09:28.680: E/AndroidRuntime(2840): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-28 09:09:28.680: E/AndroidRuntime(2840): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-28 09:09:28.680: E/AndroidRuntime(2840): at dalvik.system.NativeStart.main(Native Method)
当我打开它，它工作正常崩溃后，立即如果我等待约20分钟，然后尝试再次打开它，它会崩溃，并且同样的过程重演，任何人都有我关于发生了什么？
可以请你指出线283 – Toppers 2014-10-28 07:29:33
使用的AsyncTask为什么使用线程加载新 – 2014-10-28 07:29:37
：适配器.notifyDataSetChanged（）; – 2014-10-28 07:30:10