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Summary: Inherited Constants | Inherited Fields | Ctors | Methods | Inherited Methods

# MergeCursor

`public class MergeCursor`
`` `extends AbstractCursor` ``

java.lang.Object
↳ | android.database.AbstractCursor
| ↳ | android.database.MergeCursor

A convenience class that lets you present an array of Cursors as a single linear Cursor. The schema of the cursors presented is entirely up to the creator of the MergeCursor, and may be different if that is desired. Calls to getColumns, getColumnIndex, etc will return the value for the row that the MergeCursor is currently pointing at.

## Summary

### Inherited constants
From interface `android.database.Cursor`
`int` | `FIELD_TYPE_BLOB` Value returned by `getType(int)` if the specified column type is blob
`int` | `FIELD_TYPE_FLOAT` Value returned by `getType(int)` if the specified column type is float
`int` | `FIELD_TYPE_INTEGER` Value returned by `getType(int)` if the specified column type is integer
`int` | `FIELD_TYPE_NULL` Value returned by `getType(int)` if the specified column is null
`int` | `FIELD_TYPE_STRING` Value returned by `getType(int)` if the specified column type is string

### Inherited fields
From class `android.database.AbstractCursor`
`protected boolean` | `mClosed` This field is deprecated. Use `isClosed()` instead.
`protected ContentResolver` | `mContentResolver` This field is deprecated. Do not use.
`protected int` | `mPos` This field is deprecated. Use `getPosition()` instead.

### Public constructors
`MergeCursor(Cursor[] cursors)`

### Public methods
`void` | `close()` Closes the Cursor, releasing all of its resources and making it completely invalid.
`void` | `deactivate()` Deactivates the Cursor, making all calls on it fail until `requery()` is called.
`byte[]` | `getBlob(int column)` Returns the value of the requested column as a byte array.
`String[]` | `getColumnNames()` Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.
`int` | `getCount()` Returns the numbers of rows in the cursor.
`double` | `getDouble(int column)` Returns the value of the requested column as a double.
`float` | `getFloat(int column)` Returns the value of the requested column as a float.
`int` | `getInt(int column)` Returns the value of the requested column as an int.
`long` | `getLong(int column)` Returns the value of the requested column as a long.
`short` | `getShort(int column)` Returns the value of the requested column as a short.
`String` | `getString(int column)` Returns the value of the requested column as a String.
`int` | `getType(int column)` Returns data type of the given column's value.
`boolean` | `isNull(int column)` Returns `true` if the value in the indicated column is null.
`boolean` | `onMove(int oldPosition, int newPosition)` This function is called every time the cursor is successfully scrolled to a new position, giving the subclass a chance to update any state it may have.
`void` | `registerContentObserver(ContentObserver observer)` Register an observer that is called when changes happen to the content backing this cursor.
`void` | `registerDataSetObserver(DataSetObserver observer)` Register an observer that is called when changes happen to the contents of the this cursors data set, for example, when the data set is changed via `requery()`, `deactivate()`, or `close()`.
`boolean` | `requery()` Performs the query that created the cursor again, refreshing its contents.
`void` | `unregisterContentObserver(ContentObserver observer)` Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.
`void` | `unregisterDataSetObserver(DataSetObserver observer)` Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.

### Inherited methods
From class `android.database.AbstractCursor`
`void` | `checkPosition()` This function throws CursorIndexOutOfBoundsException if the cursor position is out of bounds.
`void` | `close()` Closes the Cursor, releasing all of its resources and making it completely invalid.
`void` | `copyStringToBuffer(int columnIndex, CharArrayBuffer buffer)` Retrieves the requested column text and stores it in the buffer provided.
`void` | `deactivate()` Deactivates the Cursor, making all calls on it fail until `requery()` is called.
`void` | `fillWindow(int position, CursorWindow window)` Copies cursor data into the window.
`void` | `finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`byte[]` | `getBlob(int column)` Returns the value of the requested column as a byte array.
`int` | `getColumnCount()` Return total number of columns
`int` | `getColumnIndex(String columnName)` Returns the zero-based index for the given column name, or -1 if the column doesn't exist.
`int` | `getColumnIndexOrThrow(String columnName)` Returns the zero-based index for the given column name, or throws `IllegalArgumentException` if the column doesn't exist.
`String` | `getColumnName(int columnIndex)` Returns the column name at the given zero-based column index.
`abstract String[]` | `getColumnNames()` Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.
`abstract int` | `getCount()` Returns the numbers of rows in the cursor.
`abstract double` | `getDouble(int column)` Returns the value of the requested column as a double.
`Bundle` | `getExtras()` Returns a bundle of extra values.
`abstract float` | `getFloat(int column)` Returns the value of the requested column as a float.
`abstract int` | `getInt(int column)` Returns the value of the requested column as an int.
`abstract long` | `getLong(int column)` Returns the value of the requested column as a long.
`Uri` | `getNotificationUri()` Return the URI at which notifications of changes in this Cursor's data will be delivered, as previously set by `setNotificationUri(ContentResolver, Uri)`.
`List<Uri>` | `getNotificationUris()` Return the URIs at which notifications of changes in this Cursor's data will be delivered, as previously set by `setNotificationUris(ContentResolver, List)`.
`final int` | `getPosition()` Returns the current position of the cursor in the row set.
`abstract short` | `getShort(int column)` Returns the value of the requested column as a short.
`abstract String` | `getString(int column)` Returns the value of the requested column as a String.
`int` | `getType(int column)` Returns data type of the given column's value.
`Object` | `getUpdatedField(int columnIndex)` This method is deprecated. Always returns null since Cursors do not support updating rows
`boolean` | `getWantsAllOnMoveCalls()` onMove() will only be called across processes if this method returns true.
`CursorWindow` | `getWindow()` If the cursor is backed by a `CursorWindow`, returns a pre-filled window with the contents of the cursor, otherwise null.
`final boolean` | `isAfterLast()` Returns whether the cursor is pointing to the position after the last row.
`final boolean` | `isBeforeFirst()` Returns whether the cursor is pointing to the position before the first row.
`boolean` | `isClosed()` return true if the cursor is closed
`boolean` | `isFieldUpdated(int columnIndex)` This method is deprecated. Always returns false since Cursors do not support updating rows
`final boolean` | `isFirst()` Returns whether the cursor is pointing to the first row.
`final boolean` | `isLast()` Returns whether the cursor is pointing to the last row.
`abstract boolean` | `isNull(int column)` Returns `true` if the value in the indicated column is null.
`final boolean` | `move(int offset)` Move the cursor by a relative amount, forward or backward, from the current position.
`final boolean` | `moveToFirst()` Move the cursor to the first row.
`final boolean` | `moveToLast()` Move the cursor to the last row.
`final boolean` | `moveToNext()` Move the cursor to the next row.
`final boolean` | `moveToPosition(int position)` Move the cursor to an absolute position.
`final boolean` | `moveToPrevious()` Move the cursor to the previous row.
`void` | `onChange(boolean selfChange)` Subclasses must call this method when they finish committing updates to notify all observers.
`boolean` | `onMove(int oldPosition, int newPosition)` This function is called every time the cursor is successfully scrolled to a new position, giving the subclass a chance to update any state it may have.
`void` | `registerContentObserver(ContentObserver observer)` Register an observer that is called when changes happen to the content backing this cursor.
`void` | `registerDataSetObserver(DataSetObserver observer)` Register an observer that is called when changes happen to the contents of the this cursors data set, for example, when the data set is changed via `requery()`, `deactivate()`, or `close()`.
`boolean` | `requery()` Performs the query that created the cursor again, refreshing its contents.
`Bundle` | `respond(Bundle extras)` This is an out-of-band way for the the user of a cursor to communicate with the cursor.
`void` | `setExtras(Bundle extras)` Sets a `Bundle` that will be returned by `getExtras()`.
`void` | `setNotificationUri(ContentResolver cr, Uri notifyUri)` Specifies a content URI to watch for changes.
`void` | `setNotificationUris(ContentResolver cr, List<Uri> notifyUris)` Similar to `setNotificationUri(android.content.ContentResolver, android.net.Uri)`, except this version allows to watch multiple content URIs for changes.
`void` | `unregisterContentObserver(ContentObserver observer)` Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.
`void` | `unregisterDataSetObserver(DataSetObserver observer)` Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.
From class `java.lang.Object`
`Object` | `clone()` Creates and returns a copy of this object.
`boolean` | `equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void` | `finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>` | `getClass()` Returns the runtime class of this `Object`.
`int` | `hashCode()` Returns a hash code value for the object.
`final void` | `notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void` | `notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String` | `toString()` Returns a string representation of the object.
`final void` | `wait(long timeout, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void` | `wait(long timeout)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void` | `wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.
From interface `android.database.CrossProcessCursor`
`abstract void` | `fillWindow(int position, CursorWindow window)` Copies cursor data into the window.
`abstract CursorWindow` | `getWindow()` Returns a pre-filled window that contains the data within this cursor.
`abstract boolean` | `onMove(int oldPosition, int newPosition)` This function is called every time the cursor is successfully scrolled to a new position, giving the subclass a chance to update any state it may have.
From interface `android.database.Cursor`
`abstract void` | `close()` Closes the Cursor, releasing all of its resources and making it completely invalid.
`abstract void` | `copyStringToBuffer(int columnIndex, CharArrayBuffer buffer)` Retrieves the requested column text and stores it in the buffer provided.
`abstract void` | `deactivate()` This method is deprecated. Since `requery()` is deprecated, so too is this.
`abstract byte[]` | `getBlob(int columnIndex)` Returns the value of the requested column as a byte array.
`abstract int` | `getColumnCount()` Return total number of columns
`abstract int` | `getColumnIndex(String columnName)` Returns the zero-based index for the given column name, or -1 if the column doesn't exist.
`abstract int` | `getColumnIndexOrThrow(String columnName)` Returns the zero-based index for the given column name, or throws `IllegalArgumentException` if the column doesn't exist.
`abstract String` | `getColumnName(int columnIndex)` Returns the column name at the given zero-based column index.
`abstract String[]` | `getColumnNames()` Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.
`abstract int` | `getCount()` Returns the numbers of rows in the cursor.
`abstract double` | `getDouble(int columnIndex)` Returns the value of the requested column as a double.
`abstract Bundle` | `getExtras()` Returns a bundle of extra values.
`abstract float` | `getFloat(int columnIndex)` Returns the value of the requested column as a float.
`abstract int` | `getInt(int columnIndex)` Returns the value of the requested column as an int.
`abstract long` | `getLong(int columnIndex)` Returns the value of the requested column as a long.
`abstract Uri` | `getNotificationUri()` Return the URI at which notifications of changes in this Cursor's data will be delivered, as previously set by `setNotificationUri(ContentResolver, Uri)`.
`default List<Uri>` | `getNotificationUris()` Return the URIs at which notifications of changes in this Cursor's data will be delivered, as previously set by `setNotificationUris(ContentResolver, List)`.
`abstract int` | `getPosition()` Returns the current position of the cursor in the row set.
`abstract short` | `getShort(int columnIndex)` Returns the value of the requested column as a short.
`abstract String` | `getString(int columnIndex)` Returns the value of the requested column as a String.
`abstract int` | `getType(int columnIndex)` Returns data type of the given column's value.
`abstract boolean` | `getWantsAllOnMoveCalls()` onMove() will only be called across processes if this method returns true.
`abstract boolean` | `isAfterLast()` Returns whether the cursor is pointing to the position after the last row.
`abstract boolean` | `isBeforeFirst()` Returns whether the cursor is pointing to the position before the first row.
`abstract boolean` | `isClosed()` return true if the cursor is closed
`abstract boolean` | `isFirst()` Returns whether the cursor is pointing to the first row.
`abstract boolean` | `isLast()` Returns whether the cursor is pointing to the last row.
`abstract boolean` | `isNull(int columnIndex)` Returns `true` if the value in the indicated column is null.
`abstract boolean` | `move(int offset)` Move the cursor by a relative amount, forward or backward, from the current position.
`abstract boolean` | `moveToFirst()` Move the cursor to the first row.
`abstract boolean` | `moveToLast()` Move the cursor to the last row.
`abstract boolean` | `moveToNext()` Move the cursor to the next row.
`abstract boolean` | `moveToPosition(int position)` Move the cursor to an absolute position.
`abstract boolean` | `moveToPrevious()` Move the cursor to the previous row.
`abstract void` | `registerContentObserver(ContentObserver observer)` Register an observer that is called when changes happen to the content backing this cursor.
`abstract void` | `registerDataSetObserver(DataSetObserver observer)` Register an observer that is called when changes happen to the contents of the this cursors data set, for example, when the data set is changed via `requery()`, `deactivate()`, or `close()`.
`abstract boolean` | `requery()` This method is deprecated. Don't use this. Just request a new cursor, so you can do this asynchronously and update your list view once the new cursor comes back.
`abstract Bundle` | `respond(Bundle extras)` This is an out-of-band way for the the user of a cursor to communicate with the cursor.
`abstract void` | `setExtras(Bundle extras)` Sets a `Bundle` that will be returned by `getExtras()`.
`abstract void` | `setNotificationUri(ContentResolver cr, Uri uri)` Register to watch a content URI for changes.
`default void` | `setNotificationUris(ContentResolver cr, List<Uri> uris)` Similar to `setNotificationUri(android.content.ContentResolver, android.net.Uri)`, except this version allows to watch multiple content URIs for changes.
`abstract void` | `unregisterContentObserver(ContentObserver observer)` Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.
`abstract void` | `unregisterDataSetObserver(DataSetObserver observer)` Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.
From interface `java.io.Closeable`
`abstract void` | `close()` Closes this stream and releases any system resources associated with it.
From interface `java.lang.AutoCloseable`
`abstract void` | `close()` Closes this resource, relinquishing any underlying resources.

## Public constructors

### MergeCursor

    public MergeCursor (Cursor[] cursors)

Parameters
`cursors` | `Cursor`

## Public methods

### close

    public void close ()

Closes the Cursor, releasing all of its resources and making it completely invalid. Unlike `deactivate()` a call to `requery()` will not make the Cursor valid again.

### deactivate

    public void deactivate ()

Deactivates the Cursor, making all calls on it fail until `requery()` is called. Inactive Cursors use fewer resources than active Cursors. Calling `requery()` will make the cursor active again.

### getBlob

    public byte[] getBlob (int column)

Returns the value of the requested column as a byte array.

The result and whether this method throws an exception when the column value is null or the column type is not a blob type is implementation-defined.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`byte[]` | the value of that column as a byte array.

### getColumnNames

    public String[] getColumnNames ()

Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result.

Returns
`String[]` | the names of the columns returned in this query.

### getCount

    public int getCount ()

Returns the numbers of rows in the cursor.

Returns
`int` | the number of rows in the cursor. Value is 0 or greater

### getDouble

    public double getDouble (int column)

Returns the value of the requested column as a double.

The result and whether this method throws an exception when the column value is null, the column type is not a floating-point type, or the floating-point value is not representable as a `double` value is implementation-defined.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`double` | the value of that column as a double.

### getFloat

    public float getFloat (int column)

Returns the value of the requested column as a float.

The result and whether this method throws an exception when the column value is null, the column type is not a floating-point type, or the floating-point value is not representable as a `float` value is implementation-defined.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`float` | the value of that column as a float.

### getInt

    public int getInt (int column)

Returns the value of the requested column as an int.

The result and whether this method throws an exception when the column value is null, the column type is not an integral type, or the integer value is outside the range [`Integer.MIN_VALUE`, `Integer.MAX_VALUE`] is implementation-defined.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`int` | the value of that column as an int.

### getLong

    public long getLong (int column)

Returns the value of the requested column as a long.

The result and whether this method throws an exception when the column value is null, the column type is not an integral type, or the integer value is outside the range [`Long.MIN_VALUE`, `Long.MAX_VALUE`] is implementation-defined.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`long` | the value of that column as a long.

### getShort

    public short getShort (int column)

Returns the value of the requested column as a short.

The result and whether this method throws an exception when the column value is null, the column type is not an integral type, or the integer value is outside the range [`Short.MIN_VALUE`, `Short.MAX_VALUE`] is implementation-defined.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`short` | the value of that column as a short.

### getString

    public String getString (int column)

Returns the value of the requested column as a String.

The result and whether this method throws an exception when the column value is null or the column type is not a string type is implementation-defined.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`String` | the value of that column as a String.

### getType

    public int getType (int column)

Returns data type of the given column's value. The preferred type of the column is returned but the data may be converted to other types as documented in the get-type methods such as `getInt(int)`, `getFloat(int)` etc.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`int` | column value type Value is `FIELD_TYPE_NULL`, `FIELD_TYPE_INTEGER`, `FIELD_TYPE_FLOAT`, `FIELD_TYPE_STRING`, or `FIELD_TYPE_BLOB`

### isNull

    public boolean isNull (int column)

Returns `true` if the value in the indicated column is null.

Parameters
`column` | `int`: the zero-based index of the target column. Value is 0 or greater

Returns
`boolean` | whether the column value is null.

### onMove

    public boolean onMove (int oldPosition,
                    int newPosition)

This function is called every time the cursor is successfully scrolled to a new position, giving the subclass a chance to update any state it may have. If it returns false the move function will also do so and the cursor will scroll to the beforeFirst position.

Parameters
`oldPosition` | `int`: the position that we're moving from
`newPosition` | `int`: the position that we're moving to

Returns
`boolean` | true if the move is successful, false otherwise

### registerContentObserver

    public void registerContentObserver (ContentObserver observer)

Register an observer that is called when changes happen to the content backing this cursor. Typically the data set won't change until `requery()` is called.

Parameters
`observer` | `ContentObserver`: the object that gets notified when the content backing the cursor changes.

### registerDataSetObserver

    public void registerDataSetObserver (DataSetObserver observer)

Register an observer that is called when changes happen to the contents of the this cursors data set, for example, when the data set is changed via `requery()`, `deactivate()`, or `close()`.

Parameters
`observer` | `DataSetObserver`: the object that gets notified when the cursors data set changes.

### requery

    public boolean requery ()

Performs the query that created the cursor again, refreshing its contents. This may be done at any time, including after a call to `deactivate()`. Since this method could execute a query on the database and potentially take a while, it could cause ANR if it is called on Main (UI) thread. A warning is printed if this method is being executed on Main thread.

Returns
`boolean` | true if the requery succeeded, false if not, in which case the cursor becomes invalid.

### unregisterContentObserver

    public void unregisterContentObserver (ContentObserver observer)

Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.

Parameters
`observer` | `ContentObserver`: the object to unregister.

### unregisterDataSetObserver

    public void unregisterDataSetObserver (DataSetObserver observer)

Unregister an observer that has previously been registered with this cursor via `registerContentObserver(ContentObserver)`.

Parameters
`observer` | `DataSetObserver`: the object to unregister.

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