public
final
class
CursorJoiner
extends Object
implements
Iterator<CursorJoiner.Result>,
Iterable<CursorJoiner.Result>
| java.lang.Object | |
| ↳ | android.database.CursorJoiner |
Does a join on two cursors using the specified columns. The cursors must already be sorted on each of the specified columns in ascending order. This joiner only supports the case where the tuple of key column values is unique.
Typical usage:
Developers
CursorJoiner joiner = new CursorJoiner(cursorA, keyColumnsofA, cursorB, keyColumnsofB);
for (CursorJointer.Result joinerResult : joiner) {
switch (joinerResult) {
case LEFT:
// handle case where a row in cursorA is unique
break;
case RIGHT:
// handle case where a row in cursorB is unique
break;
case BOTH:
// handle case where a row with the same key is in both cursors
break;
}
}
Nested classes | |
|---|---|
enum |
CursorJoiner.Result
The result of a call to next(). |
Public constructors | |
|---|---|
CursorJoiner(Cursor cursorLeft, String[] columnNamesLeft, Cursor cursorRight, String[] columnNamesRight)
Initializes the CursorJoiner and resets the cursors to the first row. |
|
Public methods | |
|---|---|
boolean
|
hasNext()
Returns whether or not there are more rows to compare using next(). |
Iterator<CursorJoiner.Result>
|
iterator()
Returns an iterator over elements of type |
CursorJoiner.Result
|
next()
Returns the comparison result of the next row from each cursor. |
void
|
remove()
Removes from the underlying collection the last element returned by this iterator (optional operation). |
Inherited methods | |
|---|---|
 From
class
java.lang.Object
| |
From
interface
java.util.Iterator
| |
From
interface
java.lang.Iterable
| |
CursorJoiner (Cursor cursorLeft, String[] columnNamesLeft, Cursor cursorRight, String[] columnNamesRight)
Initializes the CursorJoiner and resets the cursors to the first row. The left and right column name arrays must have the same number of columns.
| Parameters | |
|---|---|
cursorLeft |
Cursor:
The left cursor to compare |
columnNamesLeft |
String:
The column names to compare from the left cursor |
cursorRight |
Cursor:
The right cursor to compare |
columnNamesRight |
String:
The column names to compare from the right cursor
|
boolean hasNext ()
Returns whether or not there are more rows to compare using next().
| Returns | |
|---|---|
boolean |
true if there are more rows to compare |
Iterator<CursorJoiner.Result> iterator ()
Returns an iterator over elements of type T.
| Returns | |
|---|---|
Iterator<CursorJoiner.Result> |
an Iterator. |
CursorJoiner.Result next ()
Returns the comparison result of the next row from each cursor. If one cursor has no more rows but the other does then subsequent calls to this will indicate that the remaining rows are unique.
The caller must check that hasNext() returns true before calling this.
Once next() has been called the cursors specified in the result of the call to next() are guaranteed to point to the row that was indicated. Reading values from the cursor that was not indicated in the call to next() will result in undefined behavior.
| Returns | |
|---|---|
CursorJoiner.Result |
LEFT, if the row pointed to by the left cursor is unique, RIGHT if the row pointed to by the right cursor is unique, BOTH if the rows in both cursors are the same. |
void remove ()
Removes from the underlying collection the last element returned
by this iterator (optional operation). This method can be called
only once per call to next(). The behavior of an iterator
is unspecified if the underlying collection is modified while the
iteration is in progress in any way other than by calling this
method.