How do I return a boolean from AsyncTask?

Question

I have some EditTexts that a user enters an ftp address, username, password, port anda testConnection button. If a connection is successfully estabished it returns a boolean value of true.

boolean status = ftpConnect(_address, _username, _password,_port);
                ftpDisconnect();

                if (status == true) {
                 Toast.makeText(SiteManager.this, "Connection Succesful",
                 Toast.LENGTH_LONG).show();
                 } else {
                 Toast.makeText(SiteManager.this,
                 "Connection Failed:" + status, Toast.LENGTH_LONG).show();

                 }

I'm reworking my code to use AsyncTasks to perform the various ftp operations, but how can I pass back a boolean value if a connection is successfully made?

testConnection.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                _name = etSitename.getText().toString();
                _address = etAddress.getText().toString();
                _username = etUsername.getText().toString();
                _password = etPassword.getText().toString();
                _port = Integer.parseInt(etPort.getText().toString());

                AsyncConnectTask task = new AsyncConnectTask(SiteManager.this,
                        _address, _username, _password, _port);
                task.execute();
                // boolean status = ftpConnect(_address, _username, _password,
                // _port);
                // ftpDisconnect();

                // if (status == true) {
                // Toast.makeText(SiteManager.this, "Connection Succesful",
                // Toast.LENGTH_LONG).show();
                // savesite.setVisibility(0);
                // } else {
                // Toast.makeText(SiteManager.this,
                // "Connection Failed:" + status, Toast.LENGTH_LONG)
                // .show();

                // }
            }
        });

And my AsyncTask

public class AsyncConnectTask extends AsyncTask<Void, Void, Void> {
    private Context mContext;
    private FTPHelper ftpHelper = new FTPHelper();
    private String _address;
    private String _user;
    private String _pass;
    private int _port;
    ProgressDialog progressDialog;

    public AsyncConnectTask(Context context, String address, String user,
            String pass, int port) {
        mContext = context;
        _address = address;
        _user = user;
        _pass = pass;
        _port = port;
    }

    // declare other objects as per your need
    @Override
    protected void onPreExecute() {
        progressDialog = ProgressDialog.show(mContext, "Please wait for ",
                "Process Description Text", true);

        // do initialization of required objects objects here
    };

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

        boolean status = ftpHelper.ftpConnect(_address, _user, _pass, _port);
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        progressDialog.dismiss();
    };
}

you want the status value to get back on the UI Thread? – Blackbelt May 25 '13 at 17:24 — Blackbelt, May 25 '13 at 17:24

Blackbelt · Accepted Answer · 2014-07-24T09:11:57.680

public interface MyInterface {
    public void myMethod(boolean result);
}

public class AsyncConnectTask extends AsyncTask<Void, Void, Boolean> {

    private MyInterface mListener;


    public AsyncConnectTask(Context context, String address, String user,
        String pass, int port, MyInterface mListener) {
        mContext = context;
        _address = address;
        _user = user;
        _pass = pass;
        _port = port;
        this.mListener  = mListener;
    }

    @Override
    protected Boolean doInBackground(Void... params) {
        ....
        return result;
   }


    @Override
    protected void onPostExecute(Boolean result) {
        if (mListener != null) 
            mListener.myMethod(result);
    }
}

AsyncConnectTask task = new AsyncConnectTask(SiteManager.this,
                        _address, _username, _password, _port,  new MyInterface() {
    @Override
    public void myMethod(boolean result) {
        if (result == true) {
            Toast.makeText(SiteManager.this, "Connection Succesful",
            Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(SiteManager.this, "Connection Failed:" + status, Toast.LENGTH_LONG).show();
        } 
    }
});

task.execute();

If you call myMethod from onPostExecute the code inside it will run on the UI Thread. Otherwise you need to post a Runnable through a Handler

I ended up using your answer because I really like this approach. — RapsFan1981, May 25 '13 at 18:47
I prefer to implement the delagete pattern and do not rely on the context — Blackbelt, Jul 04 '13 at 07:31
@Blackbelt If I am trasnfering array , not boolean ` myMethod(ArrayLisy result)` how would I check it ? — Moudiz, Oct 15 '15 at 09:25
@Moudiz in the same way. Just change `boolean` with the type of the object you want to pass. E.g `ArrayList results` or `byte[] result` — Blackbelt, Oct 15 '15 at 09:27

score 13 · Answer 2 · answered May 25 '13 at 17:25

public class AsyncConnectTask extends AsyncTask<Void, Void, Boolean> {

@Override
    protected Boolean doInBackground(Void... params) {
               ....
               return true; /* or false */
}


@Override
    protected void onPostExecute(Boolean result) {
           // result holds what you return from doInBackground
    }
}

stinepike · Answer 3 · 2013-05-25T17:32:41.397

Declare Your asynctask like

public class AsyncConnectTask extends AsyncTask<Void, Void, Boolean>

The third parameter is the result parameter that is returned by doinbackground. (The first one is asynctask param and second one is progress parameter)

so your do in background and onpostexecute will be

@Override
protected Boolean doInBackground(Void... params) {

    boolean status = ftpHelper.ftpConnect(_address, _user, _pass, _port);
    return status;
}

@Override
protected void onPostExecute(Boolean result) {
    // use the result
    super.onPostExecute(result);
    progressDialog.dismiss();
};

Remember that the value returned by doInBackground is cathced by onPostExecute as parameter. so use this in the onPostExecute method. you can update your UI in in this method also.

Thanks! Gotta wait 3 more mins before I can accept this answer. Thanks for the explanation — RapsFan1981, May 25 '13 at 17:33

How do I return a boolean from AsyncTask?

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