Update UI in AsyncTask

Issue

my android project is having problems with Jsoup. I have a method that gets the data and then puts that data in the gui. Problem i have had is it doesnt wait for the data to be retrieved. I put it in a AsyncTask with the background method using the get data method and on post method using that data. The return on the background method is a arraylist of objects that have the information from the jsoup method.

I can't add the code i am working on but i have added a similar code to a example project. With the same problem.

Code Example Main Activity

public class MainActivity extends AppCompatActivity {

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

    TextView textView = findViewById(R.id.exampleTextview);

    ArrayList<ExampleObject> arrayList = new ArrayList<>();

    JsoupClass jsoupClass = new JsoupClass();

    arrayList = jsoupClass.getStaffinfomation(arrayList, "examplename");

    textView.setText(arrayList.get(0).getName());
}
}

Jsoup Class Example:

public class JsoupClass {


public ArrayList<ExampleObject> getStaffinfomation(final ArrayList<ExampleObject> emptyArray, final String infoFind){
    class getStaff extends AsyncTask<ArrayList<ExampleObject>, Void , ArrayList<ExampleObject>> {

        @Override
        protected ArrayList<ExampleObject> doInBackground(ArrayList<ExampleObject>[] arrayLists) {

            Document doc = Jsoup.connect(Config.ExampleURL).get();

        }
            Elements tableRows = doc.select("tr");
            for(int i = 0; i < tableRows.size(); i++) {


                if (tableRows.get(i).text().contains(infoFind)) {
                    //Store the information as a object
                    String fullname = tableRows.get(i).select("td").get(0).select("a").text();

                    emptyArray.add(new ExampleObject(fullname));




                    }
                }
            }

            getStaff getStaff = new getStaff();
            getStaff.execute();
            return null;

        }
}

Object Class

public class ExampleObject {
private String name;
public ExampleObject(String name){
    this.name = name;
}

public String getName(){
    return name;
}
}

Sorry for not adding the code before, hope this makes sense :)

Solution

Your poblem

Since AsyncTask#doInBackground run in another thread rather than main thread, your result will not return immediately.It's very normal because main thread should not be blocked. Simply, do long-time task in another thread and update UI in main thread.

How to solve it

    /**
    * <p>Runs on the UI thread after {@link #doInBackground}. The
    * specified result is the value returned by {@link #doInBackground}.</p>
    * 
    * <p>This method won't be invoked if the task was cancelled.</p>
    *
    * @param result The result of the operation computed by {@link #doInBackground}.
    *
    * @see #onPreExecute
    * @see #doInBackground
    * @see #onCancelled(Object) 
    */
    @SuppressWarnings({"UnusedDeclaration"})
    @MainThread
    protected void onPostExecute(Result result) {
    }

As you see, you can implement onPostExecute method. The param Result result is what you return from doInBackground. Anything confused you can ask me.

Answered By - CoXier