Androin学习笔记五十二： SQLiteCursor(示例,出错代码)

水深无声 2022-08-22 11:24 175阅读 0赞

出处：[http://www.apihome.cn/api/android/SQLiteCursor.html][http_www.apihome.cn_api_android_SQLiteCursor.html]

## android.database.sqlite   类 SQLiteCursor ##

java.lang.Object
      android.database.AbstractCursor
          android.database.AbstractWindowedCursor
              android.database.sqlite.SQLiteCursor

所有已实现的接口：

CrossProcessCursor, Cursor

--------------------

public class SQLiteCursor
       
        extends AbstractWindowedCursor

A Cursor implementation that exposes results from a query on a SQLiteDatabase.

--------------------

<table style="color:rgb(0,0,0); font-size:12px; line-height:20px"> 
 <tbody> 
 <tr style="background:rgb(204,204,255)"> 
 <th align="left" colspan="2">方法摘要</th> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;void</code></td> 
 <td><code>close()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Closes the Cursor, releasing all of its resources and making it completely invalid.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;boolean</code></td> 
 <td><code>commitUpdates(Map&lt;? extends Long,? extends Map&lt;String,Object&gt;&gt;&nbsp;additionalValues)</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;已过时。&nbsp;&nbsp;</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;void</code></td> 
 <td><code>deactivate()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Deactivates the Cursor, making all calls on it fail until Cursor.requery() is called.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;boolean</code></td> 
 <td><code>deleteRow()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;已过时。&nbsp;&nbsp;</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;int</code></td> 
 <td><code>getColumnIndex(String&nbsp;columnName)</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns the zero-based index for the given column name, or -1 if the column doesn't exist.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;String[]</code></td> 
 <td><code>getColumnNames()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;int</code></td> 
 <td><code>getCount()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Returns the numbers of rows in the cursor.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;SQLiteDatabase</code></td> 
 <td><code>getDatabase()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;boolean</code></td> 
 <td><code>onMove(int&nbsp;oldPosition, int&nbsp;newPosition)</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;void</code></td> 
 <td><code>registerDataSetObserver(DataSetObserver&nbsp;observer)</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;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 Cursor.requery(), Cursor.deactivate(), or Cursor.close().</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;boolean</code></td> 
 <td><code>requery()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Performs the query that created the cursor again, refreshing its contents.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;void</code></td> 
 <td><code>setLoadStyle(int&nbsp;initialRead, int&nbsp;maxRead)</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;support for a cursor variant that doesn't always read all results initialRead is the initial number of items that cursor window reads if query contains more than this number of items, a thread will be created and handle the left over items so that caller can show results as soon as possible</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;void</code></td> 
 <td><code>setSelectionArguments(String[]&nbsp;selectionArgs)</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Changes the selection arguments.</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;void</code></td> 
 <td><code>setWindow(CursorWindow&nbsp;window)</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Set a new cursor window to cursor, usually set a remote cursor window</td> 
 </tr> 
 <tr style=""> 
 <td align="right"><code>&nbsp;boolean</code></td> 
 <td><code>supportsUpdates()</code>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;已过时。&nbsp;&nbsp;</td> 
 </tr> 
 </tbody> 
</table>

<table style="color:rgb(0,0,0); font-size:12px; line-height:20px"> 
 <tbody> 
 <tr style="background:rgb(238,238,255)"> 
 <th align="left">从类 android.database.AbstractCursor 继承的方法</th> 
 </tr> 
 <tr style=""> 
 <td><code>abortUpdates, commitUpdates, deactivateInternal, fillWindow, getColumnCount, getColumnIndexOrThrow, getColumnName, getExtras, getPosition, getWantsAllOnMoveCalls, hasUpdates, isAfterLast, isBeforeFirst, isClosed, isFirst, isLast, move, moveToFirst, moveToLast, moveToNext, moveToPosition, moveToPrevious, registerContentObserver, respond, setNotificationUri, unregisterContentObserver, unregisterDataSetObserver, update, updateBlob, updateDouble, updateFloat, updateInt, updateLong, updateShort, updateString, updateToNull</code></td> 
 </tr> 
 </tbody> 
</table>

<table style="color:rgb(0,0,0); font-size:12px; line-height:20px"> 
 <tbody> 
 <tr style="background:rgb(238,238,255)"> 
 <th align="left">从类 java.lang.Object 继承的方法</th> 
 </tr> 
 <tr style=""> 
 <td><code>equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait</code></td> 
 </tr> 
 </tbody> 
</table>

<table style="color:rgb(0,0,0); font-size:12px; line-height:20px"> 
 <tbody> 
 <tr style="background:rgb(204,204,255)"> 
 <th align="left" colspan="1">构造方法详细信息</th> 
 </tr> 
 </tbody> 
</table>

### SQLiteCursor ###

public SQLiteCursor(SQLiteDatabase db,
                        SQLiteCursorDriver driver,
                        String editTable,
                        SQLiteQuery query)

Execute a query and provide access to its result set through a Cursor interface. For a query such as: `SELECT name, birth, phone FROM myTable WHERE ... LIMIT 1,20 ORDER BY...` the column names (name, birth, phone) would be in the projection argument and everything from `FROM` onward would be in the params argument. This constructor has package scope.

参数：

`db` \- a reference to a Database object that is already constructed and opened

`editTable` \- the name of the table used for this query

`query` \- the rest of the query terms cursor is finalized

<table style="color:rgb(0,0,0); font-size:12px; line-height:20px"> 
 <tbody> 
 <tr style="background:rgb(204,204,255)"> 
 <th align="left" colspan="1">方法详细信息</th> 
 </tr> 
 </tbody> 
</table>

### setLoadStyle ###

public void setLoadStyle(int initialRead,
                             int maxRead)

support for a cursor variant that doesn't always read all results initialRead is the initial number of items that cursor window reads if query contains more than this number of items, a thread will be created and handle the left over items so that caller can show results as soon as possible

参数：

`initialRead` \- initial number of items that cursor read

`maxRead` \- leftover items read at maxRead items per time

--------------------

### registerDataSetObserver ###

public void registerDataSetObserver(DataSetObserver observer)

从接口 `Cursor` 复制的描述

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 Cursor.requery(), Cursor.deactivate(), or Cursor.close().

指定者：

接口 `Cursor` 中的 `registerDataSetObserver`

覆盖：

类 `AbstractCursor` 中的 `registerDataSetObserver`

参数：

`observer` \- the object that gets notified when the cursors data set changes.

另请参见：

Cursor.unregisterDataSetObserver(DataSetObserver)

--------------------

### getDatabase ###

public SQLiteDatabase getDatabase()

the SQLiteDatabase that this cursor is associated with.

--------------------

### onMove ###

public boolean onMove(int oldPosition,
                          int newPosition)

从类 `AbstractCursor` 复制的描述

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.

指定者：

接口 `CrossProcessCursor` 中的 `onMove`

覆盖：

类 `AbstractCursor` 中的 `onMove`

参数：

`oldPosition` \- the position that we're moving from

`newPosition` \- the position that we're moving to

true if the move is successful, false otherwise

--------------------

### getCount ###

public int getCount()

从接口 `Cursor` 复制的描述

Returns the numbers of rows in the cursor.

指定者：

接口 `Cursor` 中的 `getCount`

指定者：

类 `AbstractCursor` 中的 `getCount`

the number of rows in the cursor.

--------------------

### getColumnIndex ###

public int getColumnIndex(String columnName)

从接口 `Cursor` 复制的描述

Returns the zero-based index for the given column name, or -1 if the column doesn't exist. If you expect the column to exist use Cursor.getColumnIndexOrThrow(String) instead, which will make the error more clear.

指定者：

接口 `Cursor` 中的 `getColumnIndex`

覆盖：

类 `AbstractCursor` 中的 `getColumnIndex`

参数：

`columnName` \- the name of the target column.

the zero-based column index for the given column name, or -1 if the column name does not exist.

另请参见：

Cursor.getColumnIndexOrThrow(String)

--------------------

### deleteRow ###

public boolean deleteRow()

已过时。

从接口 `Cursor` 复制的描述

Removes the row at the current cursor position from the underlying data store. After this method returns the cursor will be pointing to the row after the row that is deleted. This has the side effect of decrementing the result of count() by one.

The query must have the row ID column in its selection, otherwise this call will fail.

指定者：

接口 `Cursor` 中的 `deleteRow`

覆盖：

类 `AbstractCursor` 中的 `deleteRow`

whether the record was successfully deleted.

--------------------

### getColumnNames ###

public String[] getColumnNames()

从接口 `Cursor` 复制的描述

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.

指定者：

接口 `Cursor` 中的 `getColumnNames`

指定者：

类 `AbstractCursor` 中的 `getColumnNames`

the names of the columns returned in this query.

--------------------

### supportsUpdates ###

public boolean supportsUpdates()

已过时。

从接口 `Cursor` 复制的描述

Returns `true` if the cursor supports updates.

指定者：

接口 `Cursor` 中的 `supportsUpdates`

覆盖：

类 `AbstractCursor` 中的 `supportsUpdates`

whether the cursor supports updates.

--------------------

### commitUpdates ###

public boolean commitUpdates(Map<? extends Long,? extends Map<String,Object>> additionalValues)

已过时。

从接口 `Cursor` 复制的描述

Atomically commits all updates to the backing store, as well as the updates included in values. After completion, this method leaves the data in an inconsistent state and you should call Cursor.requery() before reading data from the cursor again.

指定者：

接口 `Cursor` 中的 `commitUpdates`

覆盖：

类 `AbstractCursor` 中的 `commitUpdates`

参数：

`additionalValues` \- A map from row IDs to Maps associating column names with updated values. A null value indicates the field should be removed.

whether the operation succeeded.

--------------------

### deactivate ###

public void deactivate()

从接口 `Cursor` 复制的描述

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

指定者：

接口 `Cursor` 中的 `deactivate`

覆盖：

类 `AbstractCursor` 中的 `deactivate`

--------------------

### close ###

public void close()

从接口 `Cursor` 复制的描述

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

指定者：

接口 `Cursor` 中的 `close`

覆盖：

类 `AbstractCursor` 中的 `close`

--------------------

### requery ###

public boolean requery()

从接口 `Cursor` 复制的描述

Performs the query that created the cursor again, refreshing its contents. This may be done at any time, including after a call to Cursor.deactivate().

指定者：

接口 `Cursor` 中的 `requery`

覆盖：

类 `AbstractCursor` 中的 `requery`

true if the requery succeeded, false if not, in which case the cursor becomes invalid.

--------------------

### setWindow ###

public void setWindow(CursorWindow window)

从类 `AbstractWindowedCursor` 复制的描述

Set a new cursor window to cursor, usually set a remote cursor window

覆盖：

类 `AbstractWindowedCursor` 中的 `setWindow`