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A library that encapsulates the repeatable actions of Android Cursors.
package com.venmo.cursor;
import android.content.ContentResolver;
import android.database.CharArrayBuffer;
import android.database.ContentObserver;
import android.database.DataSetObserver;
import android.net.Uri;
import android.os.Bundle;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import static com.venmo.cursor.CursorUtils.nextDocumentHelper;
import static com.venmo.cursor.CursorUtils.previousDocumentHelper;
/**
* A convenience class to turn a {@link List} into a {@link android.database.Cursor}. Useful to
* combine one data set which is backed by a {@link List} with another which is a backed by a
* {@link
* android.database.Cursor} using a {@link com.venmo.cursor.IterableMergeCursor}.
*/
public class CursorList implements List, IterableCursor {
private static final String _ID = "_id";
private static final int _ID_INDEX = 0;
private List mList;
private int mPosition = 0;
/**
* Decorate the {@code list} as both a {@link android.database.Cursor} and also a {@link List}
*/
public CursorList(List list) {
if (list == null) {
throw new NullPointerException("List parameter must be non-null");
}
mList = list;
}
@Override
public E peek() {
return mList.get(mPosition);
}
@Override
public E nextDocument() {
return nextDocumentHelper(this);
}
@Override
public E previousDocument() {
return previousDocumentHelper(this);
}
@Override
public int getCount() {
return mList.size();
}
@Override
public int getPosition() {
return mPosition;
}
@Override
public boolean move(int offset) {
mPosition += offset;
return clampPosition();
}
@Override
public boolean moveToPosition(int position) {
mPosition = position;
return clampPosition();
}
/**
* Helper for keeping {@link #mPosition} in bounds.
*
* @return false if mPosition was modified, true otherwise
*/
private boolean clampPosition() {
if (mPosition < 0) {
mPosition = -1;
return false;
} else if (mPosition > mList.size()) { // TODO should this be >= instead of >
mPosition = mList.size();
return false;
}
return true;
}
@Override
public boolean moveToFirst() {
mPosition = 0;
return mList.isEmpty();
}
@Override
public boolean moveToLast() {
mPosition = mList.size() - 1;
return mList.isEmpty();
}
@Override
public boolean moveToNext() {
return move(1);
}
@Override
public boolean moveToPrevious() {
return move(-1);
}
@Override
public boolean isFirst() {
return mPosition == 0;
}
@Override
public boolean isLast() {
return mPosition == (mList.size() - 1);
}
@Override
public boolean isBeforeFirst() {
return mPosition < 0;
}
@Override
public boolean isAfterLast() {
return mPosition >= mList.size();
}
/**
* Unsupported since {@link CursorList}s aren't backed by columns.
*/
@Override
public int getColumnIndex(String columnName) {
if (_ID.equals(columnName)) {
return _ID_INDEX;
}
return -1;
}
/**
* Unsupported since {@link CursorList}s aren't backed by columns.
*/
@Override
public int getColumnIndexOrThrow(String columnName) throws IllegalArgumentException {
int result = getColumnIndex(columnName);
if (result == -1) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
return result;
}
/**
* Unsupported since {@link CursorList}s aren't backed by columns.
*/
@Override
public String getColumnName(int columnIndex) {
if (columnIndex == _ID_INDEX) {
return _ID;
}
return null;
}
/**
* Unsupported since {@link CursorList}s aren't backed by columns.
*/
@Override
public String[] getColumnNames() {
return new String[]{_ID};
}
/**
* Unsupported since {@link CursorList}s aren't backed by columns.
*/
@Override
public int getColumnCount() {
return 1;
}
/**
* Unsupported since {@link CursorList}s aren't backed by columns.
*/
@Override
public byte[] getBlob(int columnIndex) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public String getString(int columnIndex) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public short getShort(int columnIndex) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public int getInt(int columnIndex) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public long getLong(int columnIndex) {
if (columnIndex == _ID_INDEX) {
return mPosition;
}
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public float getFloat(int columnIndex) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public double getDouble(int columnIndex) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public int getType(int columnIndex) {
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Override
public boolean isNull(int columnIndex) {
if (columnIndex == _ID_INDEX) {
return false;
}
throw new IllegalArgumentException("CursorList is not backed by columns.");
}
@Deprecated
@Override
public void deactivate() {
// noop
}
@Deprecated
@Override
public boolean requery() {
// noop
return false;
}
@Override
public void close() {
mList = null;
}
@Override
public boolean isClosed() {
return mList == null;
}
@Override
public void registerContentObserver(ContentObserver observer) {
// noop
}
@Override
public void unregisterContentObserver(ContentObserver observer) {
// noop
}
@Override
public void registerDataSetObserver(DataSetObserver observer) {
// noop
}
@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
// noop
}
@Override
public void setNotificationUri(ContentResolver cr, Uri uri) {
// noop
}
@Override
public Uri getNotificationUri() {
return null;
}
@Override
public boolean getWantsAllOnMoveCalls() {
return false;
}
@Override
public Bundle getExtras() {
return Bundle.EMPTY;
}
@Override
public Bundle respond(Bundle extras) {
return Bundle.EMPTY;
}
@Override
public void add(int location, E object) {
mList.add(location, object);
}
@Override
public boolean add(E object) {
return mList.add(object);
}
@Override
public boolean addAll(int location, Collection collection) {
return mList.addAll(location, collection);
}
@Override
public boolean addAll(Collection collection) {
return mList.addAll(collection);
}
@Override
public void clear() {
mList.clear();
}
@Override
public boolean contains(Object object) {
return mList.contains(object);
}
@Override
public boolean containsAll(Collection collection) {
return mList.containsAll(collection);
}
@Override
public E get(int location) {
return mList.get(location);
}
@Override
public int indexOf(Object object) {
return mList.indexOf(object);
}
@Override
public boolean isEmpty() {
return mList.isEmpty();
}
@Override
public Iterator iterator() {
return mList.iterator();
}
@Override
public int lastIndexOf(Object object) {
return mList.lastIndexOf(object);
}
@Override
public ListIterator listIterator() {
return mList.listIterator();
}
@Override
public ListIterator listIterator(int location) {
return mList.listIterator(location);
}
@Override
public E remove(int location) {
return mList.remove(location);
}
@Override
public boolean remove(Object object) {
return mList.remove(object);
}
@Override
public boolean removeAll(Collection collection) {
return mList.removeAll(collection);
}
@Override
public boolean retainAll(Collection collection) {
return mList.retainAll(collection);
}
@Override
public E set(int location, E object) {
return mList.set(location, object);
}
@Override
public int size() {
return mList.size();
}
@Override
public CursorList subList(int start, int end) {
return new CursorList(mList.subList(start, end));
}
@Override
public Object[] toArray() {
return mList.toArray();
}
@Override
public T[] toArray(T[] array) {
return mList.toArray(array);
}
}