・ OnPostExecute ()

A method that is used in doInBackground () to display the result of doInBackground () on the UI thread side. Use the AsyncTask argument Result.

・ PublishedProgress ()

Please when you want to use the progress display! When you run publishProgress () on doInBackground (), the Android system runs onProgressUpdate () on the UI thread.

・ OnProgressUpdate ()

When you run publishProgress () on doInBackground (), the Android system runs onProgressUpdate () on the UI thread. Refer to the argument of AsyncTask for the argument

Sample code: execute () and doInBackground ()

--Subclass MainActivity.java
AsyncTask <> and execute execute () --Extend AsyncTask <> class to generate MyAsyncTask class
doInBackground () executes the process by execute () of MainActivity.java (to do). doInBackground () receives an argument from execute () and uses it for processing.

public class MainActivity extends AppCompatActivity {

    public static TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Create a task instance. execute execute()Argument onInBackground()Pass to
        // new MyAsyncTask().execute();But OK
        MyAsyncTask myAsyncTask = new MyAsyncTask();
        myAsyncTask.execute();

    }
}

class MyAsyncTask extends AsyncTask<Void,Void,Void> {
    @Override
    protected Void doInBackground(Void... aVoid) {
        // todo
        Log.d("msg","In MyAsyncTask");
        return null;
    }
}

Sample code: Try putting in some methods

Code that changes the display of textView every 3 seconds

• MyActivity.onCreate()
  myAsncTask.excute("In doInBackground")
• class MyAsyncTask
  
  • onPreExecute()
    textView.setText("onPreExecute")
  • doInBackground()
    sleep(10003)　->　publishProgress(string[0])　->　sleep(10003)　->　return "End doInBackground"
  • onProgressUpdate()
    textView.setText(string[0])
  • onPostExecute()
    textView.setText(s)

public class MainActivity extends AppCompatActivity {

    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.textView);

        //Create a task instance. execute execute()Argument onInBackground()Pass to
        // new MyAsyncTask<>.execute();But OK
        MyAsyncTask myAsyncTask = new MyAsyncTask();
        // doInBackground()String to("In doInBackground")Pass
        // onPreExecute()After processing doInBackground()Run
        myAsyncTask.execute("In doInBackground");

    }

    class MyAsyncTask extends AsyncTask<String,String, String> {

        // execute("In doInBackground")Execute before processing. Displayed in textView of UI thread
        @Override
        protected void onPreExecute(){
            textView.setText("onPreExecute");
        }

        // execute()String from"In doInBackground"To receive
        @Override
        protected String doInBackground(String... string) {

            //Wait 3 seconds
            try {
                sleep(1000*3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            //Display textView during doInBackground processing onPublishUpdate()Call
            publishProgress(string[0]);

            //Wait 3 seconds
            try {
                sleep(1000*3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            // onPostExecute()String to"End doInBackground"give
            return "End doInBackground";
        }

        //publishProgress in doInBackground()Receives a string from and displays it in the textView of the UI thread
        protected void onProgressUpdate(String... string){
            textView.setText(string[0]);
        }

        // doInBackground()Return value from("End doInBackground")And display it in the textView of the UI thread
        @Override
        protected void onPostExecute(String s){
            textView.setText(s);
        }
    }
}

Pass parameters from Activity to AsyncTask

Pass multiple parameters one by one

MainActivity

...
new MyAsyncTask().execute("param1","param2");

MyAsyncTask

...
@Override
protected String doInBackground(String... string){
   String param1 = string[0];
   String param2 = string[1];
return null
}

Pass multiple parameters as an array

MainActivity

Map<String,String> map = new HashMap<String,String>();
   map.put("param1","data1");
   map.put("param2","data2");
   map.put("param3","data3");

new MyAsyncTask().execute(map);

MyAsyncTask

public class MyAsyncTask extends AsyncTask<Map<String,String>,Void,Map<String,String>>{

   @Override
   protected Map<String,String> doInBackground(Map<String,String>... map){
      Map<String,String> mp = map[0];
      //If mp is Json
      // JSONObject jsonMap = new JSONObject(mp);
      return mp;
   }

   @Override
   protected void onPostExecute(Map<String,String> mp){
      super.onPostExecute(mp);
      String val1 = mp.get("param1"); //data1 was stored in val1
      String val2 = mp.get("param1"); //data2 was stored in val2
      String val3 = mp.get("param3"); //data3 was stored in val3
   }
}

It took a while. The turtle's walk as usual.