Viewpager, Cursor and Fragment

Question

I am new to the viewpager and was wondering if anyone could point me to a tutorial or source code of a project that uses a viewpager with fragments and a database. I\'ve see

Answer 1

I have posted some answers in the other posts related to your question.

Here's some of the links that you might find helpful.

First Link: To get custom views in every page slide. (Accepted answer)

Android:How to create different view in ViewPager?

Second: How to properly use fragments with ViewPager. (Accepted answer)

How to properly use fragments with ViewPager?

If those two links are not that helpful, try this:

public class AllActivities extends FragmentActivity implements ActionBar.TabListener {

    public ViewPager viewPager;
    private AllPagesAdapter mAdapter;
    private ActionBar actionBar;
    private String [] tabs = {"Android","CoreJava","J2EE","Database","Web Services"};

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

        //Initializing all stuff
        viewPager = (ViewPager)findViewById(R.id.pager);

        actionBar = getActionBar();
        mAdapter = new AllPagesAdapter(getSupportFragmentManager());
        viewPager.setAdapter(mAdapter);
        actionBar.setHomeButtonEnabled(true);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);



        //Add the tabs here
        for(String tab_name:tabs){
            actionBar.addTab(actionBar.newTab().setText(tab_name).setTabListener(this));
        }

        viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener(){

            @Override
        public void onPageSelected(int position){

                //on Page change, that particular page should be selected
                actionBar.setSelectedNavigationItem(position);
            }

            @Override
                public void onPageScrolled(int arg0,float arg1,int arg2){

            }
            @Override
        public void onPageScrollStateChanged(int position){

            }

        });
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction fragmentTransaction) {

        viewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction fragmentTransaction) {



    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction fragmentTransaction) {

        viewPager.setCurrentItem(tab.getPosition());

    }
}

//This is one of the fragment and assume that Expandablelistview is your list view.. In both the cases, i am setting the adapter in the onActivityCreated() method.
public class Android extends android.support.v4.app.Fragment {



    ExpandableListAdapter listAdapter;
    // private ExpandableListView expListView;
    List<String> listDataHeader;
    HashMap<String, List<String>> listDataChild;
    ListView lv1;
    private static final String QUESTION = "question";
    private static final String ANSWERS = "answer";


    // ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>();

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {


        View mikeview = inflater.inflate(R.layout.androidlayout, container, false);

        return mikeview;

    }



    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);


        ExpandableListView expListView = null;
        try{
            expListView = (ExpandableListView) getActivity().findViewById(R.id.androidExpandableList);
            }
        catch (Exception e){

            e.printStackTrace();
        }




        new Thread(){


            @Override
            public void run(){



            }
        }.start();

        try {
            setParent();
            prepareChild();
        } catch (Exception e) {
            e.printStackTrace();
        }




        ExpandableListAdapter listAdapter = new ExpandableListAdapter(getActivity(), listDataHeader, listDataChild);
        expListView.setAdapter(listAdapter);




        // Listview on child click listener
        expListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {

            @Override
            public boolean onChildClick(ExpandableListView parent, View v,
                                        int groupPosition, int childPosition, long id) {
                /*Toast.makeText(
                        getActivity(),
                        listDataHeader.get(groupPosition)
                                + " : "
                                + listDataChild.get(
                                listDataHeader.get(groupPosition)).get(
                                childPosition), Toast.LENGTH_SHORT)
                        .show();*/
                return true;
            }
        });


        // Listview Group expanded listener
        expListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            @Override
            public void onGroupExpand(int groupPosition) {
               /* Toast.makeText(getActivity(),
                        listDataHeader.get(groupPosition) + " Expanded",
                        Toast.LENGTH_SHORT).show();*/
            }
        });

        // Listview Group collasped listener
        expListView.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {

            @Override
            public void onGroupCollapse(int groupPosition) {
                /*Toast.makeText(getActivity(),
                        listDataHeader.get(groupPosition) + " Collapsed",
                        Toast.LENGTH_SHORT).show();*/

            }
        });


    }


    public void setParent(){

        listDataHeader = new ArrayList<String>();

        try{

            JSONObject json = new JSONObject(loadJSONFromAsset());

            JSONArray array = json.getJSONArray("androidquestion");

            for(int my =0;my<array.length();my++){

                JSONObject c = array.getJSONObject(my);


                String topics = c.getString(QUESTION);
                listDataHeader.add(topics);
            }
        }

        catch (JSONException e) {

            e.printStackTrace();

        }

    }

    public void prepareChild() throws JSONException {

        listDataChild = new HashMap<String, List<String>>();

        try{

            JSONObject json = new JSONObject(loadJSONFromAsset());
            JSONArray array = json.getJSONArray("androidquestion");
            for(int mz = 0;mz<array.length();mz++){

                ArrayList<String> child = new ArrayList<String>();
                JSONObject d = array.getJSONObject(mz);
                String ans = d.getString(ANSWERS);
                child = new ArrayList<String>();

                child.add(ans);
                int position = mz ;

                listDataChild.put(listDataHeader.get( position),child);

            }
        }
        catch(JSONException e) {
            e.printStackTrace();

        }

    }


    public String loadJSONFromAsset() {

        String json = null;

        try {

            InputStream is = getActivity().getAssets().open("android.json");

            int size = is.available();

            byte[] buffer = new byte[size];

            is.read(buffer);

            is.close();

            json = new String(buffer, "UTF-8");

        } catch (IOException ex) {

            ex.printStackTrace();

            return null;
        }
        return json;

    }

}

    //This is the adapter.
    public class AllPagesAdapter extends FragmentStatePagerAdapter {



            public AllPagesAdapter(FragmentManager fm) {

                super(fm);

            }

            @Override
            public Fragment getItem(int index) {

        switch (index) {
            case 0:

                return new Android();

            case 1:

                return new CoreJava();
            case 2:

                return new J2EE();

            case 3:

                return new Database();

            case 4:

                return new WebServices();


        }
        return null;


    }

    @Override
    public int getCount() {
        return 5;
    }

}

//This is the adapter for my expandable list view.. in your case, your can just use the listadapter or any other adapter you want to use. This is just an optional part.
public class ExpandableListAdapter extends BaseExpandableListAdapter {

    private Context _context;
    private List<String> _listDataHeader; // header titles
    // child data in format of header title, child title
    private HashMap<String, List<String>> _listDataChild;


    public ExpandableListAdapter(Context context, List<String> listDataHeader,
                                 HashMap<String, List<String>> listChildData) {
        this._context = context;
        this._listDataHeader = listDataHeader;
        this._listDataChild = listChildData;
    }

    @Override
    public Object getChild(int groupPosition, int childPosititon) {
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .get(childPosititon);
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public View getChildView(int groupPosition, final int childPosition,
                             boolean isLastChild, View convertView, ViewGroup parent) {

        final String childText = (String) getChild(groupPosition, childPosition);

        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) this._context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.newlistitems,null);

        }

        TextView txtListChild = (TextView) convertView
                .findViewById(R.id.newlistviewitems);

        txtListChild.setText(childText);
        return convertView;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        return this._listDataHeader.get(groupPosition);
    }

    @Override
    public int getGroupCount() {
        return this._listDataHeader.size();
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
                             View convertView, ViewGroup parent) {
        String headerTitle = (String) getGroup(groupPosition);
        if (convertView == null) {
            LayoutInflater myInflater = (LayoutInflater) this._context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = myInflater.inflate(R.layout.newlistgroup, null);
        }

        TextView lblListHeader = (TextView) convertView
                .findViewById(R.id.newlistviewgroup);
        lblListHeader.setTypeface(null, Typeface.BOLD);
        lblListHeader.setText(headerTitle);

        return convertView;
    }

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

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }
}

Lemme know if you need some more examples on that..:)

Answer 2

You need to create abstract class adapter to use both cursor and pager adapter and extend to your own adapter and bind the view.

public abstract class CursorPagerAdapter extends PagerAdapter {

public static final String TAG = CursorPagerAdapter.class.getSimpleName();

protected WeakReference<Context> ctxRef;

protected boolean mDataValid;
protected boolean mAutoRequery;
protected Cursor mCursor;
protected int mRowIDColumn;

protected ChangeObserver mChangeObserver;
protected DataSetObserver mDataSetObserver;

/**
 * If set the adapter will call requery() on the cursor whenever a content change notification is
 * delivered. Implies {@link #FLAG_REGISTER_CONTENT_OBSERVER}.
 *
 * @deprecated This option is discouraged, as it results in Cursor queries being performed on the
 *             application's UI thread and thus can cause poor responsiveness or even Application
 *             Not Responding errors. As an alternative, use {@link android.app.LoaderManager} with
 *             a {@link android.content.CursorLoader}.
 */
@Deprecated
public static final int FLAG_AUTO_REQUERY = 0x01;

/**
 * If set the adapter will register a content observer on the cursor and will call {@link
 * # onContentChanged()} when a notification comes in. Be careful when using this flag: you will
 * need to unset the current Cursor from the adapter to avoid leaks due to its registered
 * observers. This flag is not needed when using a CursorAdapter with a {@link
 * android.content.CursorLoader}.
 */
public static final int FLAG_REGISTER_CONTENT_OBSERVER = 0x02;

public CursorPagerAdapter(Context context, Cursor c, int flags) {
    init(context, c, flags);
}

void init(Context context, Cursor c, int flags) {
    if ((flags & FLAG_AUTO_REQUERY) == FLAG_AUTO_REQUERY) {
        flags |= FLAG_REGISTER_CONTENT_OBSERVER;
        mAutoRequery = true;
    } else {
        mAutoRequery = false;
    }

    boolean cursorPresent = c != null;
    mCursor = c;
    mDataValid = cursorPresent;
    ctxRef = new WeakReference<>(context);
    mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1;

    if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) {
        mChangeObserver = new ChangeObserver();
        mDataSetObserver = new MyDataSetObserver();
    } else {
        mChangeObserver = null;
        mDataSetObserver = null;
    }

    if (cursorPresent) {
        if (mChangeObserver != null) {
            c.registerContentObserver(mChangeObserver);
        }

        if (mDataSetObserver != null) {
            c.registerDataSetObserver(mDataSetObserver);
        }
    }
}

public Cursor getCursor() {
    return mCursor;
}

@Override
public int getCount() {
    if (mDataValid && mCursor != null)
        return mCursor.getCount();
    else
        return 0;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
    if (!mDataValid) {
        throw new IllegalStateException("this should only be called when the cursor is valid");
    }

    if (!mCursor.moveToPosition(position)) {
        throw new IllegalStateException("couldn't move cursor to position " + position);
    }

    Context context = ctxRef.get();
    if (context != null) {
        View v = newView(context, mCursor, (ViewGroup) container);
        bindView(v, context, mCursor);

        ((ViewPager) container).addView(v);

        return v;
    } else {
        throw new IllegalStateException("context is null");
    }
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    ((ViewPager) container).removeView((View) object);
}

@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}

@Override
public boolean isViewFromObject(View view, Object o) {
    return view == o;
}

public abstract View newView(Context context, Cursor cursor, ViewGroup parent);

public abstract void bindView(View view, Context context, Cursor cursor);

public void changeCursor(Cursor cursor) {
    Cursor old = swapCursor(cursor);
    if (old != null) {
        old.close();
    }
}

public Cursor swapCursor(Cursor newCursor) {
    if (newCursor == mCursor) return null;

    Cursor oldCursor = mCursor;
    if (oldCursor != null) {
        if (mChangeObserver != null) {
            oldCursor.unregisterContentObserver(mChangeObserver);
        }
        if (mDataSetObserver != null) {
            oldCursor.unregisterDataSetObserver(mDataSetObserver);
        }
    }

    mCursor = newCursor;
    if (newCursor != null) {
        if (mChangeObserver != null) {
            newCursor.registerContentObserver(mChangeObserver);
        }

        if (mDataSetObserver != null) {
            newCursor.registerDataSetObserver(mDataSetObserver);
        }

        mRowIDColumn = newCursor.getColumnIndexOrThrow("_id");
        mDataValid = true;
        // notify the observers about the new cursor
        notifyDataSetChanged();
    } else {
        mRowIDColumn = -1;
        mDataValid = false;
        notifyDataSetChanged();
    }

    return oldCursor;
}

private void onContentChange() {
    if (mAutoRequery && mCursor != null && !mCursor.isClosed()) {
        mDataValid = mCursor.requery();
    }
}

private class ChangeObserver extends ContentObserver {

    public ChangeObserver() {
        super(new Handler());
    }

    /**
     *
     * @return True if self-change notifications should be delivered to the observer.
     */
    @Override
    public boolean deliverSelfNotifications() {
        return true;
    }

    /**
     * This method is called when a content change occurs.
     * @param selfChange
     */
    @Override
    public void onChange(boolean selfChange) {
        onContentChange();
    }
}

private class MyDataSetObserver extends DataSetObserver {

    @Override
    public void onChanged() {
        mDataValid = true;
        notifyDataSetChanged();
    }

    @Override
    public void onInvalidated() {
        mDataValid = false;
        notifyDataSetChanged();
    }
}

}

Sample Adapter (in kotlin):

class SampleAdapter(context: Context, cursor: Cursor?, autoQuery: Int): CursorPagerAdapter(context, cursor, autoQuery) {

internal var mContext: Context
internal var mLayoutInflater: LayoutInflater
internal var aQuery: AQuery
val imageWidth = Helper.getDisplayWidth(context)
init {
    mContext = context
    mLayoutInflater = mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
    aQuery = AQuery(context)
}

override fun newView(context: Context?, cursor: Cursor?, parent: ViewGroup?): View {
    return mLayoutInflater.inflate(R.layout.your_item_row, parent, false)
}

override fun bindView(view: View?, context: Context?, cursor: Cursor?) {
    val sampleVo = SampleVo.getValueFromCursor(cursor)
    val tvTitle = view?.findViewById<AppCompatTextView>(R.id.tvTitle)
    tvTitle?.text = sampleVo.title
}

Original Source: link