从另一个线程更改UI

Question

UPDATED: I updated it seith some logs inputs, than you for your help.

I'm applying the following code:

@Override
public void run() {

     byte[] bytes = null;

     int TIMEOUT = 5000;

     int status = connection.bulkTransfer(ep, bytes, ep.getMaxPacketSize(), TIMEOUT);

     Log.d(TAG, "status: " + status);

     write_to_screen( bytes );

}

public void write_to_screen( byte[] bytes  ) {

    Log.d(TAG, "bytes: " + bytes);

    String str_non_final = null;

    try {

        str_non_final = new String( bytes, "UTF-8");
        Log.d(TAG, "str_non_final : " + str_non_final );

    } catch (UnsupportedEncodingException e) {

        e.printStackTrace();

    }   

    final String str = str_non_final;

    Log.d(TAG, "str: " + str);

    runOnUiThread(new Runnable() {@Override public void run()
    {
       textView7.setText( str );
       Log.d(TAG, "UI updated");
    }
    });

}   

The result of the logcat is as follows:

D/EthernetActivity(15721): open SUCCESS

D/EthernetActivity(15721): status: -1

D/EthernetActivity(15721): bytes: null

so it would seem to me that the problem is in "str_non_final = new String( bytes, "UTF-8");". What is wrong with this?

Answer 1

in this statement

str_non_final = new String( bytes, "UTF-8");

you are using byte and which is null as printed in your logcat. so it will throw the NullPointerException and your catch is able to handle only UnsupportedEncodingException .

make sure that bytes should not null before call

write_to_screen( bytes );