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/*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.content;
import android.database.Cursor;
import android.os.RemoteException;
/**
* Abstract implementation of EntityIterator that makes it easy to wrap a cursor
* that can contain several consecutive rows for an entity.
* @hide
*/
public abstract class CursorEntityIterator implements EntityIterator {
private final Cursor mCursor;
private boolean mIsClosed;
/**
* Constructor that makes initializes the cursor such that the iterator points to the
* first Entity, if there are any.
* @param cursor the cursor that contains the rows that make up the entities
*/
public CursorEntityIterator(Cursor cursor) {
mIsClosed = false;
mCursor = cursor;
mCursor.moveToFirst();
}
/**
* Returns the entity that the cursor is currently pointing to. This must take care to advance
* the cursor past this entity. This will never be called if the cursor is at the end.
* @param cursor the cursor that contains the entity rows
* @return the entity that the cursor is currently pointing to
* @throws RemoteException if a RemoteException is caught while attempting to build the Entity
*/
public abstract Entity getEntityAndIncrementCursor(Cursor cursor) throws RemoteException;
/**
* Returns whether there are more elements to iterate, i.e. whether the
* iterator is positioned in front of an element.
*
* @return {@code true} if there are more elements, {@code false} otherwise.
* @see EntityIterator#next()
*/
public final boolean hasNext() {
if (mIsClosed) {
throw new IllegalStateException("calling hasNext() when the iterator is closed");
}
return !mCursor.isAfterLast();
}
/**
* Returns the next object in the iteration, i.e. returns the element in
* front of the iterator and advances the iterator by one position.
*
* @return the next object.
* @throws java.util.NoSuchElementException
* if there are no more elements.
* @see EntityIterator#hasNext()
*/
public Entity next() {
if (mIsClosed) {
throw new IllegalStateException("calling next() when the iterator is closed");
}
if (!hasNext()) {
throw new IllegalStateException("you may only call next() if hasNext() is true");
}
try {
return getEntityAndIncrementCursor(mCursor);
} catch (RemoteException e) {
throw new RuntimeException("caught a remote exception, this process will die soon", e);
}
}
public void remove() {
throw new UnsupportedOperationException("remove not supported by EntityIterators");
}
public final void reset() {
if (mIsClosed) {
throw new IllegalStateException("calling reset() when the iterator is closed");
}
mCursor.moveToFirst();
}
/**
* Indicates that this iterator is no longer needed and that any associated resources
* may be released (such as a SQLite cursor).
*/
public final void close() {
if (mIsClosed) {
throw new IllegalStateException("closing when already closed");
}
mIsClosed = true;
mCursor.close();
}
}
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