我在片段中有一个广播接收器，它正在更新数据库，它正在从服务之一运行数据。在广播接收器中，我首先更新数据库，即使片段未打开，它也会正确更新，然后更新列表仅当该类处于活动状态时才在其他类中，这给了我错误。这是我的广播接收器，当 messagestatus=='t' 时，它将检查其他类的状态并更新该类中的列表。
private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
updateUI(intent);
}};
private void updateUI(Intent intent) {
@SuppressWarnings("unchecked")
ArrayAdapter<Message> adapter = (ArrayAdapter<Message>) getListAdapter();
Message message = null;
//Toast.makeText(getActivity().getApplicationContext(), "Yea!!! Service called", Toast.LENGTH_SHORT).show();
String messages = intent.getStringExtra("messages"); //getting received message from server class
// String senderip = intent.getStringExtra("sender");
String[] arr = messages.split(" ", 3);
String threadid = arr[0];
//Toast.makeText( getActivity().getApplicationContext(),threadid,Toast.LENGTH_SHORT).show();
char messagestatus = arr[1].charAt(0);
String msg = arr[2];
char ch = 0;
if(messagestatus=='s')
{
ch='r';
}
if(messagestatus=='t')
{
ch='t';
}
int id = Integer.parseInt(threadid);
message = datasource.createMessage(msg,ch,id);
if(ch=='r')
{
adapter.add(message);
adapter.notifyDataSetChanged();
} //It is updating the respond list or sent message responses list
try {
if (messagestatus == 't')
{
long originalId = message.getId();
Respond res = new Respond();
if (res.getActivityStatus() == true)
{
if (res.getrthreadid().compareTo(threadid) == 0)
{
res.notiffy(msg,originalId);
}
}
SResponses sres = new SResponses();
if (sres.getActivityStatus() == true)
{
if (sres.getsrthreadid().compareTo(threadid) == 0)
{
sres.notiffy(msg,originalId);
}
}
}
} catch (RuntimeException e) {
// TODO: handle exception
e.printStackTrace();
}
}
我在 SResponses 类中将更新该类中的列表视图的函数是，我的 SResponses 类是：
public class SResponses extends ListActivity{
static boolean active = false;
private DataSource datasource;
long threadid;
public static String srthreadid;
public String getsrthreadid()
{
return srthreadid;
}
public boolean getActivityStatus()
{
return active;
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.sresponses);
datasource = new DataSource(getApplicationContext());
datasource.open();
Intent intent=getIntent();
threadid= intent.getLongExtra("threadid", 0);
srthreadid=String.valueOf(threadid);
char ch='e';
List<Message> values = datasource.getAllMessages(ch);
ArrayAdapter<Message> adapter = new ArrayAdapter<Message>(getApplicationContext(), R.layout.custom_list_item, values);
setListAdapter(adapter);
}
public void notiffy(String msg,long originalId)
{
// finish();
// startActivity(getIntent());
@SuppressWarnings("unchecked")
ArrayAdapter<Message> adapter = (ArrayAdapter<Message>) getListAdapter();
Message messages = new Message();
messages.setId(originalId);
messages.setmessage(msg);
messages.setthreadid(threadid);
adapter.add(messages);
adapter.notifyDataSetChanged();
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
datasource.close();
}
@Override
public void onStart() {
super.onStart();
active = true;
}
@Override
public void onStop() {
super.onStop();
active = false;
}
}
我在列表中获取消息的方法：
public List<Message> getAllMessages(char ch) {
Cursor cursors = null;
//String thid=res.getrthreadid();
List<Message> message = new ArrayList<Message>();
if(ch=='r')
{
String queryz = "SELECT " + MySQLiteHelper.COLUMN_ID + "," + MySQLiteHelper.COLUMN_MESSAGE+","+MySQLiteHelper.COLUMN_THREADID + " FROM " + MySQLiteHelper.TABLE_NAME + " WHERE " +MySQLiteHelper.COLUMN_STATUS + "= 'r'";
cursors = database.rawQuery(queryz, null);
}
if(ch=='s')
{
String queryz = "SELECT " + MySQLiteHelper.COLUMN_ID + "," + MySQLiteHelper.COLUMN_MESSAGE+","+MySQLiteHelper.COLUMN_THREADID + " FROM " + MySQLiteHelper.TABLE_NAME + " WHERE " +MySQLiteHelper.COLUMN_STATUS + "= 's'";
cursors = database.rawQuery(queryz, null);
}
if(ch=='t')
{
Respond res=new Respond();
String queryz = "SELECT " + MySQLiteHelper.COLUMN_ID + "," + MySQLiteHelper.COLUMN_MESSAGE+","+MySQLiteHelper.COLUMN_THREADID + " FROM " + MySQLiteHelper.TABLE_NAME + " WHERE "+MySQLiteHelper.COLUMN_THREADID+ "="+res.getrthreadid();
cursors = database.rawQuery(queryz, null);
}
if(ch=='e')
{
SResponses sres=new SResponses();
String queryz = "SELECT " + MySQLiteHelper.COLUMN_ID + "," + MySQLiteHelper.COLUMN_MESSAGE+","+MySQLiteHelper.COLUMN_THREADID + " FROM " + MySQLiteHelper.TABLE_NAME + " WHERE "+MySQLiteHelper.COLUMN_THREADID+ "="+sres.getsrthreadid();
cursors = database.rawQuery(queryz, null);
}
/*if(ch=='s')
cursor = database.query(MySQLiteHelper.TABLE_NAME,allColumns, MySQLiteHelper.COLUMN_STATUS+"="+"s", null, null, null, null);*/
cursors.moveToFirst();
while (!cursors.isAfterLast()) {
Message message1 = cursorToMessage(cursors);
message.add(message1);
cursors.moveToNext();
}
// Make sure to close the cursor
cursors.close();
return message;
}
private Message cursorToMessage(Cursor cursor) {
Message message = new Message();
message.setId(cursor.getLong(cursor.getColumnIndex("id")));
// message.setparentid(cursor.getLong(1));
message.setmessage(cursor.getString(cursor.getColumnIndex("message")));
message.setthreadid(cursor.getLong(cursor.getColumnIndex("threadid")));
// message.status(cursor.getString(4));
return message;
}
但是我收到了这个错误，我已经为此付出了很多，请帮忙。
09-18 03:56:34.469: W/System.err(22580): java.lang.NullPointerException
09-18 03:56:34.473: W/System.err(22580): at soft.b.peopleassist.SResponses.notiffy(SResponses.java:56)
09-18 03:56:34.474: W/System.err(22580): at soft.b.peopleassist.Receive.updateUI(Receive.java:122)
09-18 03:56:34.474: W/System.err(22580): at soft.b.peopleassist.Receive.access$0(Receive.java:66)
09-18 03:56:34.475: W/System.err(22580): at soft.b.peopleassist.Receive$1.onReceive(Receive.java:63)
09-18 03:56:34.476: W/System.err(22580): at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:785)
09-18 03:56:34.478: W/System.err(22580): at android.os.Handler.handleCallback(Handler.java:615)
09-18 03:56:34.479: W/System.err(22580): at android.os.Handler.dispatchMessage(Handler.java:92)
09-18 03:56:34.479: W/System.err(22580): at android.os.Looper.loop(Looper.java:153)
09-18 03:56:34.481: W/System.err(22580): at android.app.ActivityThread.main(ActivityThread.java:5000)
09-18 03:56:34.481: W/System.err(22580): at java.lang.reflect.Method.invokeNative(Native Method)
09-18 03:56:34.483: W/System.err(22580): at java.lang.reflect.Method.invoke(Method.java:511)
09-18 03:56:34.484: W/System.err(22580): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
09-18 03:56:34.485: W/System.err(22580): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
09-18 03:56:34.485: W/System.err(22580): at dalvik.system.NativeStart.mai
n(Native Method)