/**
* Removes an object at a given index. This also deletes the object from the underlying Realm.
*
* <p>Using this method while iterating the list can result in a undefined behavior. Use {@link
* io.realm.RealmResults.RealmResultsIterator#remove()} instead.
*
* @param index the array index identifying the object to be removed.
* @return always return {@code null}.
* @throws IllegalStateException if the corresponding Realm is closed or in an incorrect thread.
*/
@Override
public E remove(int index) {
realm.checkIfValid();
TableOrView table = getTable();
table.remove(index);
return null; // Returning the object doesn't make sense, since it could no longer access any
// data.
}
/**
* Finds the maximum date.
*
* @param fieldName the field to look for the maximum date. If fieldName is not of Date type, an
* exception is thrown.
* @return if no objects exist or they all have {@code null} as the value for the given date
* field, {@code null} will be returned. Otherwise the maximum date is returned. When
* determining the maximum date, objects with {@code null} values are ignored.
* @throws java.lang.IllegalArgumentException if fieldName is not a Date field.
*/
public Date maxDate(String fieldName) {
realm.checkIfValid();
long columnIndex = table.getColumnIndex(fieldName);
if (table.getColumnType(columnIndex) == RealmFieldType.DATE) {
return table.maximumDate(columnIndex);
} else {
throw new IllegalArgumentException(String.format(TYPE_MISMATCH, fieldName, "Date"));
}
}
/**
* Returns the average of a given field.
*
* @param fieldName the field to calculate average on. Only number fields are supported.
* @return the average for the given field amongst objects in query results. This will be of type
* double for all types of number fields. If no objects exist or they all have {@code null} as
* the value for the given field, {@code 0} will be returned. When computing the average,
* objects with {@code null} values are ignored.
* @throws java.lang.IllegalArgumentException if the field is not a number type.
*/
public double average(String fieldName) {
realm.checkIfValid();
long columnIndex = table.getColumnIndex(fieldName);
switch (table.getColumnType(columnIndex)) {
case INTEGER:
return table.averageLong(columnIndex);
case DOUBLE:
return table.averageDouble(columnIndex);
case FLOAT:
return table.averageFloat(columnIndex);
default:
throw new IllegalArgumentException(
String.format(TYPE_MISMATCH, fieldName, "int, float or double"));
}
}
private RealmResults(BaseRealm realm, TableOrView table, Class<E> classSpec) {
this.realm = realm;
this.classSpec = classSpec;
this.table = table;
this.pendingQuery = null;
this.query = null;
this.currentTableViewVersion = table.sync();
}
// aux. method used by sort methods
private long getColumnIndex(String fieldName) {
if (fieldName.contains(".")) {
throw new IllegalArgumentException(
"Sorting using child object properties is not supported: " + fieldName);
}
long columnIndex = table.getColumnIndex(fieldName);
if (columnIndex < 0) {
throw new IllegalArgumentException(String.format("Field '%s' does not exist.", fieldName));
}
return columnIndex;
}
/** Notifies all registered listeners. */
void notifyChangeListeners() {
if (listeners != null && !listeners.isEmpty()) {
// table might be null (if the async query didn't complete
// but we have already registered listeners for it)
if (pendingQuery != null && !isCompleted) return;
// FIXME: still waiting for Core to provide a fix
// for crash when calling _sync_if_needed on a cleared View.
// https://github.com/realm/realm-core/pull/1390
long version = table.sync();
if (currentTableViewVersion != version) {
currentTableViewVersion = version;
for (RealmChangeListener listener : listeners) {
listener.onChange();
}
}
}
}
/**
* Removes all objects from the list. This also deletes the objects from the underlying Realm.
*
* @throws IllegalStateException if the corresponding Realm is closed or in an incorrect thread.
*/
public void clear() {
realm.checkIfValid();
TableOrView table = getTable();
table.clear();
}
/**
* Removes and returns the last object in the list. This also deletes the object from the
* underlying Realm.
*
* <p>Using this method while iterating the list can result in a undefined behavior. Use {@link
* io.realm.RealmResults.RealmResultsListIterator#removeLast()} instead.
*
* @throws IllegalStateException if the corresponding Realm is closed or in an incorrect thread.
*/
public void removeLast() {
realm.checkIfValid();
TableOrView table = getTable();
table.removeLast();
}