Passing Arraylist From Asynctask To Pageradapter

hope you fine and well, i have the following main class : public class MainActivity extends AppCompatActivity { Activity activity; ViewPager viewPager; CustomAdapter

Solution 1:

what i want is to pass this list to the following class in order to use it in the imageView and textView in the viewPager

Then simply pass in the list as a parameter to the adapter and add a member variable for it. The usage of this adapter is at the bottom of this post, because I want to mention some other stuff.

classCustomAdapterextendsPagerAdapter{
    private Context ctx;
    private List<Student> data;

    public CustomAdapter(Context ctx, List<Student> students) {
        this.ctx = ctx;
        this.data = students;
    }

If you want to use that data variable in the instantiateItem method, then you can do Student s = this.data.get(position); and use the various methods on the Student object to load the TextView or ImageView.

---

Please note that you will need an image loading library (Picasso, Glide, Fresco, etc.) to load a URL into an ImageView. While on the topic of libraries, though, you will save yourself much development time by looking into Gson for JSON parsing and Retrofit or Volley for HTTP network calls with JSON data.

---

As for your usage of the AsyncTask, passing around the Activity variable is bad practice. Try to use an asynchronous callback to the Activity instead.

publicinterfaceAsyncResponse<T> {
    voidonResponse(T response);
} 

publicclassConnectionAsyncTaskextendsAsyncTask<String, Void, List<Student>> {

    privateAsyncResponse<List<Student>> callback;

    publicConnectionAsyncTask(AsyncResponse<List<Student>> callback) {
        this.callback = callback;
    }

    @OverrideprotectedList<User> doInBackground(String... params) {
        String url = params[0];
        final List<Student> students = newArrayList<Student>();

        // TODO: JSON stuffreturn students;
    }

    @OverrideprotectedvoidonPostExecute(List<Student> result) {
        if (this.callback != null) {
            this.callback.onResponse(result);
        } else {
            Log.w("ConnectionAsyncTask", "Ignoring result");
        }
    }
}

publicclassSampleViewPagerActivityextendsActivity{

    private ViewPager pager;
    private PagerAdapter adapter;
    private ArrayList<Student> students;
    private ProgressDialog progress;

    @Overrideprotected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 1. Inflate a layout
        setContentView(R.layout.viewpager_activity);

        // 2. Initialize the viewsthis.pager = (ViewPager) findViewById(R.id.pager);
        this.progress = new ProgressDialog(this);
        this.progress.setTitle("Loading");
        this.progress.setMessage("Please wait");

        // 3. Populate the views with datathis.students = new ArrayList<Student>();
        this.adapter = new CustomAdapter(this, students);
        this.pager.setAdapter(adapter);

        // This code runs later, after 'execute' is called and the response is returned
        ConnectionAsyncTask task = new ConnectionAsyncTask(new AsyncResponse<List<Student>>() {
            @Overridepublic void onResponse(List<Student> response) {
                students.clear();
                students.addAll(response);
                adapter.notifyDataSetChanged();

                progress.hide();
            }
        });

        // Optionally show some progress while waitingthis.progress.show();

        // TODO: Use real URL
        task.execute("http://www.somesite.com/data");
    }
}