How To Create Asynctask To Prevent Networkonmainthreadexception

I'm new to android application development. I tried to develop an android server client chat for my first project. This is the code for the client side. When the client press btnJ

Solution 1:

Change your code as:

   btnJoin.setOnClickListener(newOnClickListener() {
    @OverridepublicvoidonClick(View view){

              newLongOperation().execute("");

    }
}

privateclassLongOperationextendsAsyncTask<String, Void, String> {
     Socket socket = null;
     String strresult="";
        DataOutputStream dataOutputStream = null;
        DataInputStream dataInputStream = null;
          @OverrideprotectedStringdoInBackground(String... params) {

        try {
            socket = newSocket("192.168.1.4", 9092);
            dataOutputStream = newDataOutputStream(socket.getOutputStream());
            dataInputStream = newDataInputStream(socket.getInputStream());
            dataOutputStream.writeUTF("Hello server!");
            strresult.append(dataInputStream.readUTF() + "\n");
         //   txtIP.append(dataInputStream.readUTF() + "\n");
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (dataOutputStream != null) {
                try {
                    dataOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (dataInputStream != null) {
                try {
                    dataInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

                return strresult;
          }      

          @OverrideprotectedvoidonPostExecute(String result) {
                TextView txtIP= (TextView) findViewById(R.id.txtIP);
              //  txtIP.append(result + "\n");
                txtIP.setText(result + "\n");

          }

          @OverrideprotectedvoidonPreExecute() {
          }

    }  

Solution 2:

Use AsyncTask like this :

First have it nested in your class, it should look similar to :

privateclassCommunicatorextendsAsyncTask<Void, Void, Boolean> {
    String tmp;
    String err;

    @OverrideprotectedBooleandoInBackground() {

        try {
                socket = newSocket("192.168.1.4", 9092);
                dataOutputStream = newDataOutputStream(socket.getOutputStream());
                dataInputStream = newDataInputStream(socket.getInputStream());
                dataOutputStream.writeUTF("Hello server!");


         } catch (UnknownHostException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (socket != null) {
                    try {
                        socket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (dataOutputStream != null) {
                    try {
                        dataOutputStream.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (dataInputStream != null) {
                    try {
                        dataInputStream.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

        returntrue;
    }

    @OverrideprotectedvoidonPreExecute() {

    }

    @OverrideprotectedvoidonPostExecute(Boolean result) {
         txtIP.append(dataInputStream.readUTF() + "\n");            


    }
}

When you have AsyncTask,you can start it like this :

...
@OverridepublicvoidonClick(View v) {
Communicator c=newCommunicator();
c.execute();
}
....

Solution 3:

try to implement this code in your app

privateclassLongOperationextendsAsyncTask<Object, Integer, Object> {

        @OverrideprotectedvoidonPreExecute() {



            super.onPreExecute();
        }

        @OverrideprotectedObjectdoInBackground(Object... params) {
            //do hard work herereturn params;
        }

        @OverrideprotectedvoidonProgressUpdate(Integer... values) {


        }

        @OverrideprotectedvoidonPostExecute(Object result) {



            super.onPostExecute(result);
        }
    } 

Solution 4:

AsyncTask must be subclassed to be used. The subclass will override at least one method (doInBackground(Params...)), and most often will override a second one (onPostExecute(Result).)

Here is an example of subclassing:

privateclassDownloadFilesTaskextendsAsyncTask<URL, Integer, Long> {
     protected Long doInBackground(URL... urls) {
         int count = urls.length;
         long totalSize = 0;
         for (int i = 0; i < count; i++) {
             totalSize += Downloader.downloadFile(urls[i]);
             publishProgress((int) ((i / (float) count) * 100));
             // Escape early if cancel() is calledif (isCancelled()) break;
         }
         return totalSize;
     }

     protectedvoidonProgressUpdate(Integer... progress) {
         setProgressPercent(progress[0]);
     }

     protectedvoidonPostExecute(Long result) {
         showDialog("Downloaded " + result + " bytes");
     }
 }

Once created, a task is executed very simply:

 new DownloadFilesTask().execute(url1, url2, url3);

for more details refer below links...

http://www.vogella.com/articles/AndroidPerformance/article.html

http://developer.android.com/reference/android/os/AsyncTask.html