Question

I am trying to integrate facebook capabilities into my Android app. So, I have an adapter which is going to display a list of items. Once user clicks on a button, it will start the authentication/authorizing process. But I am having errors on my code. Have I missed out any declarations or anything? I am following the example from here

Error 1: MODE_PRIVATE cannot be resolved to a variable

Error 2: The method onActivityResult(int, int, Intent) is undefined for the type BaseAdapter

Adapter.java

public class LazyAdapter extends BaseAdapter {

Facebook facebook = new Facebook("132789674563789674");
private Activity activity;
private String[] data;
private String[] text;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader;

private static final String APP_ID = "132789674563789674";
private ProgressDialog mProgress;
private Handler mRunOnUi = new Handler();

String FILENAME = "AndroidSSO_data";
private SharedPreferences mPrefs;

public LazyAdapter(Activity a, String[] d, String[] t) {
    activity = a;
    data=d;
    text = t;
    inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    imageLoader=new ImageLoader(activity.getApplicationContext());        

}

public int getCount() {
    return data.length;
}    

public Object getItem(int position) {
    return position;
}

public long getItemId(int position) {
    return position;
}

public static class ViewHolder{
    public TextView text;
    public ImageView image;
}

public View getView(final int position, View convertView, ViewGroup parent) {
    View vi=convertView;
    ViewHolder holder;
    if(convertView==null){
        vi = inflater.inflate(R.layout.item, null);
        holder=new ViewHolder();
        holder.text=(TextView)vi.findViewById(R.id.text);;
        holder.image=(ImageView)vi.findViewById(R.id.image);
        vi.setTag(holder);

        ImageButton fbBtn = (ImageButton) vi.findViewById(R.id.fb);

        fbBtn.setOnClickListener(
                new Button.OnClickListener() {
                    public void onClick(View v) 
                    {
                        /*
                         * Get existing access_token if any
                         */
                        mPrefs = getPreferences(MODE_PRIVATE);    <--- MODE_PRIVATE cannot be resolved to a variable
                        String access_token = mPrefs.getString("access_token", null);
                        long expires = mPrefs.getLong("access_expires", 0);
                        if(access_token != null) {
                            facebook.setAccessToken(access_token);
                        }
                        if(expires != 0) {
                            facebook.setAccessExpires(expires);
                        }

                        /*
                         * Only call authorize if the access_token has expired.
                         */
                        if(!facebook.isSessionValid()) {


                        facebook.authorize(activity, new String[] {"publish_stream", "publish_checkins"}, new DialogListener() {
                            @Override
                            public void onComplete(Bundle values) 
                            {
                                //postToFacebook(String image);
                                SharedPreferences.Editor editor = mPrefs.edit();
                                editor.putString("access_token", facebook.getAccessToken());
                                editor.putLong("access_expires", facebook.getAccessExpires());
                                editor.commit();
                            }

                            @Override
                            public void onFacebookError(FacebookError error) {}

                            @Override
                            public void onError(DialogError e) {}

                            @Override
                            public void onCancel() {}
                        });
                    }
                }
                    }
            );

    }
    else
    holder=(ViewHolder)vi.getTag();

    holder.text.setText(text[position]);
    holder.image.setTag(data[position]);
    imageLoader.DisplayImage(data[position], activity, holder.image);
    return vi;

postToFacebook("");       
}//close getView


private void postToFacebook(String data) {  
    mProgress.setMessage("Posting ...");
    mProgress.show();

    AsyncFacebookRunner mAsyncFbRunner = new AsyncFacebookRunner(facebook);

    Bundle params = new Bundle();

    params.putString("message", "Visit me here!");
    params.putString("name", "My Name");
    params.putString("caption", "google.com");
    params.putString("link", "http://www.google.com");
    params.putString("description", "Visit the search engine");
    params.putString("image", data);

    mAsyncFbRunner.request("me/feed", params, "POST", new WallPostListener());
}//close posttofacebook

private final class WallPostListener extends BaseRequestListener {
    public void onComplete(final String response) {
        mRunOnUi.post(new Runnable() {
            @Override
            public void run() {
                mProgress.cancel();

                Toast.makeText(activity, "Posted to Facebook", Toast.LENGTH_SHORT).show();
            }
        });
    }//close oncomplete
}//close wallpostlistener

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);  <----- The method onActivityResult(int, int, Intent) is undefined for the type BaseAdapter

    facebook.authorizeCallback(requestCode, resultCode, data);
}


}

Answer 1

Problems:

Error 1: MODE_PRIVATE cannot be resolved to a variable

getPreferences() and MODE_PRIVATE are not available in BaseAdapter, these both are available in Context class (so it is also available in Activity) and you can access them using context.getPreferences(Context.MODE_PRIVATE);

Error 2: The method onActivityResult(int, int, Intent) is undefined
for the type BaseAdapter

onActivityResult() is method of Activity not a method of BaseAdapter

Solution:

You should put facebook authentication and post to wall related code in Activity.

and now the point is:

• how Activity will know the FB ImageButton was pressed.
• how Activity will know that it should do postToFacebook(String);

We will use interface, make an interface in your LazyAdapter like this:

public class LazyAdapter extends BaseAdapter {
    FBookTaskListener taskListener;
//--all your other class members as above in your code.
    public void setTaskListener(FBookTaskListener listener)
    {
        this.taskListener = listener;
    }

//-- here all your other stuff constructor getView() getCount() etc. as above in your code.

    public static interface FBookTaskListener{
        public void doAuthentication(); //paramas may be added if needed
        public void postToWall();  //paramas may be added if needed
    }
}

now in your LazyAdapter‘s getView() where you set OnClickListener for FBButton

fbBtn.setOnClickListener(new Button.OnClickListener() {
     public void onClick(View v)
     {
          taskListener.doAuthentication();  // will be handled in Activity :)
     }
});

now in your Activity where you set Adapter.

LazyAdapter adapter = new LazyAdapter(this, a, b);
listView.setAdapter(adapter);
adapter.setTaskListener(new FBookTaskListener(){
    public void doAuthentication()
    {
            // here all your FB authentication related stuff.
    }
    public void postToWall()
    {
        postToFacebook();
    }
});

take all method like onActivityResult() and postToFacebook() and WallPostListener in your Activity class from LazyAdapter