Suspended (exception IlegalStateException) blackberry 6.0 - blackberry

Question

Following is the code which is showing the above exception on debugging :
Firstly I am trying to call a class HTTPConnection from the below menu item.
protected MenuItem _SelectDealerItem = new MenuItem("Select Dealer",100,10)
{
public void run()
{
new HTTPConnection();
}
};
In HTTPConnection Class I am checking the connection type and calling another Class TSelectDealerScreen:
public class HTTPConnection {
ConnectionFactory _factory = new ConnectionFactory();
public HTTPConnection()
{
int[] _intTransports = {
TransportInfo.TRANSPORT_TCP_WIFI,
TransportInfo.TRANSPORT_WAP2,
TransportInfo.TRANSPORT_TCP_CELLULAR
};
for(int i=0;i<_intTransports.length;i++)
{
int transport = _intTransports[i];
if(!TransportInfo.isTransportTypeAvailable(transport)||!TransportInfo.hasSufficientCoverage(transport))
{
Arrays.removeAt(_intTransports,i);
}
}
TcpCellularOptions tcpOptions = new TcpCellularOptions();
if(!TcpCellularOptions.isDefaultAPNSet())
{
tcpOptions.setApn("My APN");
tcpOptions.setTunnelAuthUsername("user");
tcpOptions.setTunnelAuthPassword("password");
}
if(_intTransports.length>0)
{
_factory.setPreferredTransportTypes(_intTransports);
}
_factory.setTransportTypeOptions(TransportInfo.TRANSPORT_TCP_CELLULAR, tcpOptions);
_factory.setAttemptsLimit(5);
Thread t = new Thread(new Runnable()
{
public void run()
{
ConnectionDescriptor cd = _factory.getConnection("http://excellentrealtors.info/Smart-Trace/get_dealer.php");
if(cd!=null)
{
Connection c = cd.getConnection();
displayContent(c);
}
}
});
t.start();
}
private void displayContent(final Connection conn)
{
UiApplication.getUiApplication().pushScreen(new TSelectDealerScreen(conn));
}
}
In TSelectDealerScreen class i am simply trying to read the stream, but it is showing illegal state exception whenever i try to debug, I am not much familiar to blackberry programming, kindly advice.
public class TSelectDealerScreen extends MainScreen
{
RichTextField _rtfOutput = new RichTextField();
public TSelectDealerScreen(Connection conn)
{
_rtfOutput.setText("Retrieving Data.Please Wait");
add(_rtfOutput);
ContentReaderThread t = new ContentReaderThread(conn);
t.start();
}
private final class ContentReaderThread extends Thread {
private Connection _connection;
ContentReaderThread(Connection conn)
{
_connection = conn;
}
public void run()
{
String result = "";
OutputStream os = null;
InputStream is = null;
try
{
OutputConnection outputConn = (OutputConnection)_connection;
os = outputConn.openOutputStream();
String getCommand = "GET " + "/" + " HTTP/1.0\r\n\r\n";
os.write(getCommand.getBytes());
os.flush();
// Get InputConnection and read the server's response
InputConnection inputConn = (InputConnection) _connection;
is = inputConn.openInputStream();
byte[] data = net.rim.device.api.io.IOUtilities.streamToBytes(is);
result = new String(data, "US-ASCII");
// is.close();
System.out.print(result);
}
catch(Exception e)
{
result = "ERROR fetching content: " + e.toString();
}
finally
{
// Close OutputStream
if(os != null)
{
try
{
os.close();
}
catch(IOException e)
{
}
}
// Close InputStream
if(is != null)
{
try
{
is.close();
}
catch(IOException e)
{
}
}
// Close Connection
try
{
_connection.close();
}
catch(IOException ioe)
{
}
}
// Show the response received from the web server, or an error message
showContents(result);
}
}
public void showContents(final String result)
{
UiApplication.getUiApplication().invokeLater(new Runnable()
{
public void run()
{
_rtfOutput.setText(result);
}
});
}
}

Answer 1

In your HTTPConnection class, you do:
Thread t = new Thread(new Runnable()
{
public void run()
{
ConnectionDescriptor cd = _factory.getConnection("http://excellentrealtors.info/Smart-Trace/get_dealer.php");
if(cd!=null)
{
Connection c = cd.getConnection();
displayContent(c);
}
}
});
t.start();
That runs everything inside run() on a background thread. But, inside displayContent(c), you do:
UiApplication.getUiApplication().pushScreen(new TSelectDealerScreen(conn));
which is a UI operation.
Trying to modify the UI from a background thread normally causes an IllegalStateException.
I believe you just need to wrap the call to pushScreen() with this:
private void displayContent(final Connection conn) {
final UiApplication app = UiApplication.getUiApplication();
app.invokeLater(new Runnable() {
public void run() {
// this code is run on the UI thread
app.pushScreen(new TSelectDealerScreen(conn));
}
});
}
Also, if you're an Android developer, and you want help doing normal background/UI thread stuff, you might check out this other answer I wrote on "porting" AsyncTask to BlackBerry Java