SubSectionFragment.java

package vit.vithandbook.fragment;

import android.app.Fragment;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;

import java.util.ArrayList;

import vit.vithandbook.R;
import vit.vithandbook.adapter.CardListAdapter;
import vit.vithandbook.adapter.onItemClickListener;
import vit.vithandbook.helperClass.DataBaseHelper;


public class SubSectionFragment extends BackHandlerFragment {

    public String mainCategory;
    ArrayList<String> Subtopics;
    CardListAdapter rvAdapter;
    ProgressBar load;
    android.support.v7.widget.RecyclerView recyclerView;

    public static SubSectionFragment newInstance(String mainCategory) {
        SubSectionFragment frag = new SubSectionFragment();
        frag.mainCategory = mainCategory;
        return frag;
    }

    public SubSectionFragment() {

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle SavedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_sub_section, container, false);
        load = (ProgressBar) view.findViewById(R.id.ssprogressbar);
        recyclerView = (android.support.v7.widget.RecyclerView) view.findViewById(R.id.subSectionList);
        new AsyncTask<Void, Void, Void>() {

            @Override
            protected void onPreExecute() {
                load.setVisibility(View.VISIBLE);
            }

            @Override
            protected Void doInBackground(Void... params) {
                fetchSubSectionData();
                // sample data remove to test with actual data
                return null;
            }

            @Override
            protected void onPostExecute(Void res) {
                load.setVisibility(View.GONE);
                rvAdapter = new CardListAdapter(getActivity(), Subtopics);
                rvAdapter.setOnItemClickListener(new onItemClickListener() {
                    @Override
                    public void onItemClick(String data) {
                        rvItemClick(data);

                    }
                });
                recyclerView.setAdapter(rvAdapter);
                // recyclerView.setLayoutManager(new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL));
                recyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 2));
            }
        }.execute();
        return view;
    }

    @Override
    public boolean onBackPressed() {
        return false;
    }

    public void rvItemClick(String data) {
        Fragment hideFragment = getActivity().getFragmentManager().findFragmentByTag("subSectionFragment");
        Fragment articleFragment = ArticleListFragment.newInstance(data);
        getActivity().getFragmentManager().beginTransaction().setCustomAnimations(R.transition.fade_in, R.transition.fade_out, R.transition.fade_in, R.transition.fade_out)
                .hide(hideFragment).add(R.id.frame_layout_main, articleFragment, "articleListFragment").addToBackStack(null).commit();
    }

    public void fetchSubSectionData() {
        Cursor cursor = null;
        SQLiteDatabase db = null;
        try {
            db = SQLiteDatabase.openDatabase(DataBaseHelper.DB_PATH + DataBaseHelper.DB_NAME, null, SQLiteDatabase.OPEN_READWRITE);
            cursor = db.rawQuery("SELECT distinct `sub_category` from `articles` Where main_category = ?", new String[]{mainCategory});
            Subtopics = new ArrayList<String>();
            cursor.moveToFirst();
            while (!cursor.isAfterLast()) {
                Subtopics.add(cursor.getString(0));
                cursor.moveToNext();
            }
        } catch (Exception e) {
            if(db.isOpen()){
                Log.e("db issue","YES. Open");
            }
            else{
                Log.e("db issue","CLOSED");
            }
            e.printStackTrace();
        } finally {
            cursor.close();
            db.close();
        }
    }
}