/**
* 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"));
}
}
