ViewPager and Database

Question

The data is in the database, so I would usually use a CursorAdapter and work with CursorLoader in a ListView, however now I need a ViewPager instead of a ListView, and it accepts a PagerAdapter, and I just saw that it works with lists.

Is there a native pager adapter that uses a cursor or a bad one to make it work?

Thanks!

Answer 1

Based on the internal functions of the CursorAdapter I have an implementation that extends the FragmentPagerAdapter with the only difference that you will use the information obtained from Cursor to create an instance of Fragment .

package com.example; import android.content.Context; import android.database.Cursor; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.util.SparseIntArray; import android.view.ViewGroup; import java.util.HashMap; public abstract class CursorFragmentPagerAdapter extends FragmentPagerAdapter { protected boolean mDataValid; protected Cursor mCursor; protected Context mContext; protected SparseIntArray mItemPositions; protected HashMap<Object, Integer> mObjectMap; protected int mRowIDColumn; public CursorFragmentPagerAdapter(Context context, FragmentManager fm, Cursor cursor) { super(fm); init(context, cursor); } void init(Context context, Cursor c) { mObjectMap = new HashMap<Object, Integer>(); boolean cursorPresent = c != null; mCursor = c; mDataValid = cursorPresent; mContext = context; mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; } public Cursor getCursor() { return mCursor; } @Override public int getItemPosition(Object object) { Integer rowId = mObjectMap.get(object); if (rowId != null && mItemPositions != null) { return mItemPositions.get(rowId, POSITION_NONE); } return POSITION_NONE; } public void setItemPositions() { mItemPositions = null; if (mDataValid) { int count = mCursor.getCount(); mItemPositions = new SparseIntArray(count); mCursor.moveToPosition(-1); while (mCursor.moveToNext()) { int rowId = mCursor.getInt(mRowIDColumn); int cursorPos = mCursor.getPosition(); mItemPositions.append(rowId, cursorPos); } } } @Override public Fragment getItem(int position) { if (mDataValid) { mCursor.moveToPosition(position); return getItem(mContext, mCursor); } else { return null; } } @Override public void destroyItem(ViewGroup container, int position, Object object) { mObjectMap.remove(object); super.destroyItem(container, position, object); } @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); } int rowId = mCursor.getInt(mRowIDColumn); Object obj = super.instantiateItem(container, position); mObjectMap.put(obj, Integer.valueOf(rowId)); return obj; } public abstract Fragment getItem(Context context, Cursor cursor); @Override public int getCount() { if (mDataValid) { return mCursor.getCount(); } else { return 0; } } 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; mCursor = newCursor; if (newCursor != null) { mRowIDColumn = newCursor.getColumnIndexOrThrow("_id"); mDataValid = true; } else { mRowIDColumn = -1; mDataValid = false; } setItemPositions(); notifyDataSetChanged(); return oldCursor; } @Override public long getItemId(int position) { if (!mDataValid || !mCursor.moveToPosition(position)) { return super.getItemId(position); } int rowId = mCursor.getInt(mRowIDColumn); return rowId; } } 

If you need anything else besides Fragment, you can easily change the code to suit your needs.