敬酒不显示在asynctask中

Question

I am trying to get message from the server to show in toast but it does not appear. The client receives the message from the server without any errors.I have tried opening UI thread in onpost but it didn't work

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main2);
    new test().execute();

}
public class test extends AsyncTask<String,String,String>{


    @Override
    protected String doInBackground(String... params) {

        try
        {
            socket = new Socket("ip", port);
            OutputStream outToServer = socket.getOutputStream();
            DataOutputStream out = new DataOutputStream(outToServer);
            Log.i(debugString, "Connected_reg!");
            out.writeUTF("3");


            InputStream inFromServer = socket.getInputStream();
            DataInputStream in = new DataInputStream(inFromServer);
            Log.i(debugString, in.readUTF());
            string= in.readUTF();

        }
        catch (Exception e) {
            Log.e(debugString, e.getMessage());
        }


        return null;
    }


    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(String s) {

       //super.onPostExecute(s);

                Context context = getApplicationContext();
                CharSequence text = string;
                int duration = Toast.LENGTH_SHORT;
                Toast toast = Toast.makeText(context, text, duration);
                toast.show();
    }


}

Answer 1

It might be to do with the context.

I've had issues in the past with getApplicationContext not working for certain things, although can't remember what form the top of my head.

Instead of using getApplicationContext, in the activity where you call your async task put this in the constructor call. For example, assuming you are going from MainActivity change the line new test().execute(); to new test(MainActivity.this).execute();

Then in the async class create the constructor as

public test(Context context) and set a global class variable to be the value of context, and then use this in your toast.makeText instead of what is returned from getApplicationContext.

Also take a look in the logcat, see if there are any errors or exceptions being thrown, it might also be worth adding a log line in the onpostexecute method just to double check you're definetely going in there.

Answer 2

Create a constructor in the test class which receive a context and use that context in the Toast.makeText. Pass the host activity context to that constructor.

getApplicationContext() is a Context class method, AsyncTask does not inherent from that class. I suppose you are in a scope where you can invoke that method but that scope context is not valid in the scope that you are invoking the Toast.makeText method.