如何在android中正确关闭光标
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【中文标题】如何在android中正确关闭光标【英文标题】：How to properly close a cursor in android 【发布时间】：2012-10-08 16:18:25 【问题描述】：我有这个使用 sqlite 的数据库，我在关闭游标时遇到问题，它说 Application did not close the cursor or database object that was opened here 这是 logcat
10-18 08:40:56.354: E/Cursor(331): android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
10-18 08:40:56.354: E/Cursor(331): at android.database.sqlite.SQLiteCursor.<init>(SQLiteCursor.java:210)
10-18 08:40:56.354: E/Cursor(331): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:53)
10-18 08:40:56.354: E/Cursor(331): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1345)
10-18 08:40:56.354: E/Cursor(331): at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1229)
10-18 08:40:56.354: E/Cursor(331): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1184)
10-18 08:40:56.354: E/Cursor(331): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1264)
10-18 08:40:56.354: E/Cursor(331): at standard.internet.marketing.mymovingfriend.SQLHandler.checkMove(SQLHandler.java:1094)
10-18 08:40:56.354: E/Cursor(331): at standard.internet.marketing.mymovingfriend.ListMovingNames$3.onKey(ListMovingNames.java:98)
10-18 08:40:56.354: E/Cursor(331): at android.view.View.dispatchKeyEvent(View.java:3735)
10-18 08:40:56.354: E/Cursor(331): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
10-18 08:40:56.354: E/Cursor(331): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
10-18 08:40:56.354: E/Cursor(331): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
10-18 08:40:56.354: E/Cursor(331): at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
10-18 08:40:56.354: E/Cursor(331): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1667)
10-18 08:40:56.354: E/Cursor(331): at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1102)
10-18 08:40:56.354: E/Cursor(331): at android.app.Activity.dispatchKeyEvent(Activity.java:2063)
10-18 08:40:56.354: E/Cursor(331): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1643)
10-18 08:40:56.354: E/Cursor(331): at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2471)
10-18 08:40:56.354: E/Cursor(331): at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2441)
10-18 08:40:56.354: E/Cursor(331): at android.view.ViewRoot.handleMessage(ViewRoot.java:1735)
10-18 08:40:56.354: E/Cursor(331): at android.os.Handler.dispatchMessage(Handler.java:99)
10-18 08:40:56.354: E/Cursor(331): at android.os.Looper.loop(Looper.java:123)
10-18 08:40:56.354: E/Cursor(331): at android.app.ActivityThread.main(ActivityThread.java:4627)
10-18 08:40:56.354: E/Cursor(331): at java.lang.reflect.Method.invokeNative(Native Method)
10-18 08:40:56.354: E/Cursor(331): at java.lang.reflect.Method.invoke(Method.java:521)
10-18 08:40:56.354: E/Cursor(331): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
10-18 08:40:56.354: E/Cursor(331): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
10-18 08:40:56.354: E/Cursor(331): at dalvik.system.NativeStart.main(Native Method)
这个问题困扰了我 3 天。
这里有一些相关代码：
public class SQLHandler
public static final String KEY_MOVENAME = "movename";
public static final String KEY_ID1 = "_id";
public static final String KEY_ID5 = "_id";
public static final String KEY_MOVEDATE = "movedate";
public static final String KEY_TOTALMOVEWEIGHT = "totalmoveweight";
public static final String KEY_TOTALITEM = "totalitem";
private static final String DATABASE_NAME = "mymovingfriend";
private static final int DATABASE_VERSION = 1;
public static final String KEY_LISTITEMNAME = "listitemname";
public static final String KEY_LISTITEMWEIGHT = "listitemweight";
public static final String KEY_LISTITEMROOM = "listitemroom";
private static final String DATABASE_TABLE1 = "movingname";
private static final String DATABASE_TABLE5 = "listitem";
public static final String CREATE_TABLE_1 = "CREATE TABLE " + DATABASE_TABLE1 + " (" +
KEY_ID1 + " INTEGER PRIMARY KEY AUTOINCREMENT," +
KEY_MOVEDATE + " TEXT NOT NULL, " +
KEY_TOTALMOVEWEIGHT + " TEXT NOT NULL, " +
KEY_TOTALITEM + " INTEGER NOT NULL, " +
KEY_MOVENAME + " TEXT NOT NULL);";
public static final String CREATE_TABLE_2 = "CREATE TABLE " + DATABASE_TABLE2 + " (" +
KEY_ID2 + " INTEGER PRIMARY KEY AUTOINCREMENT," +
KEY_ROOMMOVEHOLDER + " TEXT NOT NULL, " +
KEY_ROOMWEIGHT + " TEXT NOT NULL, " +
KEY_ROOM + " TEXT NOT NULL);";
public static final String CREATE_TABLE_5 = "CREATE TABLE " + DATABASE_TABLE5 + " (" +
KEY_ID5 + " INTEGER PRIMARY KEY AUTOINCREMENT," +
KEY_LISTITEMNAME + " TEXT NOT NULL, " +
KEY_LISTITEMWEIGHT + " TEXT NOT NULL, " +
KEY_LISTITEMROOM + " TEXT NOT NULL);";
private DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;
private static class DbHelper extends SQLiteOpenHelper
public DbHelper(Context context)
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
@Override
public void onCreate(SQLiteDatabase db)
// TODO Auto-generated method stub
db.execSQL(CREATE_TABLE_1);
db.execSQL(CREATE_TABLE_2);
db.execSQL(CREATE_TABLE_3);
db.execSQL(CREATE_TABLE_4);
db.execSQL(CREATE_TABLE_5);
@Override
public void onUpgrade(SQLiteDatabase db, int oldversion, int newversion)
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE1);
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE2);
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE3);
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE4);
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE5);
onCreate(db);
public SQLHandler(Context c)
ourContext = c;
public SQLHandler open() throws SQLException
ourHelper = new DbHelper(ourContext);
ourDatabase = ourHelper.getWritableDatabase();
return this;
public void close()
ourDatabase.close();
ourHelper.close();
public long createMove(String smovename)
ContentValues cv = new ContentValues();
cv.put(KEY_MOVENAME, smovename);
cv.put(KEY_MOVEDATE, "Not yet set");
cv.put(KEY_TOTALMOVEWEIGHT, "0");
cv.put(KEY_TOTALITEM, 0);
return ourDatabase.insert(DATABASE_TABLE1, null, cv);
public void createList()
String[] sroom = new String[]"Kitchen", "Bedroom", "Dinning Room";
String[] sitem = new String[]"Dishwasher", "Bed", "Table";
String[] sweight = new String[]"40", "25", "15";
for (int i = 0; i < sroom.length; i++)
cv.put(KEY_LISTITEMROOM, sroom[i]);
cv.put(KEY_LISTITEMNAME, sitem[i]);
cv.put(KEY_LISTITEMWEIGHT, sweight[i]);
ourDatabase.insert(DATABASE_TABLE5, null, cv);
public void setMoveDate(String smovedate, String smovename)
ContentValues cv = new ContentValues();
cv.put(KEY_MOVEDATE, smovedate);
ourDatabase.update(DATABASE_TABLE1, cv, KEY_MOVENAME + "='" + smovename + "'", null);
public void setMoveWeight(String smoveweight, String smovename)
ContentValues cv = new ContentValues();
cv.put(KEY_TOTALMOVEWEIGHT, smoveweight);
ourDatabase.update(DATABASE_TABLE1, cv, KEY_MOVENAME + "='" + smovename + "'", null);
public void setTotalItem(String smovename, int imoveitem)
ContentValues cv = new ContentValues();
cv.put(KEY_TOTALITEM, imoveitem);
ourDatabase.update(DATABASE_TABLE1, cv, KEY_MOVENAME + "='" + smovename + "'", null);
public void renameRoom(String movename, String roomname, String currentroom)
ContentValues cv = new ContentValues();
cv.put(KEY_ROOM, roomname);
ourDatabase.update(DATABASE_TABLE2, cv, KEY_ROOMMOVEHOLDER + "='" + movename + "'" + " AND " + KEY_ROOM + "='" + currentroom + "'", null);
public void setRoomWeight(String sroomweight, String smovename, String sroomname)
ContentValues cv = new ContentValues();
cv.put(KEY_ROOMWEIGHT, sroomweight);
ourDatabase.update(DATABASE_TABLE2, cv, KEY_ROOMMOVEHOLDER + "='" + smovename + "'" + " AND " + KEY_ROOM + "='" + sroomname + "'", null);
public long addRooms(String sroommoveholder, String sroom)
ContentValues cv = new ContentValues();
cv.put(KEY_ROOMMOVEHOLDER, sroommoveholder);
cv.put(KEY_ROOM, sroom);
cv.put(KEY_ROOMWEIGHT, "0");
return ourDatabase.insert(DATABASE_TABLE2, null, cv);
public long addNewItems(String sitemmoveholder, String sroomholder, String sitemname, String sitemvalue, String sitemweight)
ContentValues cv = new ContentValues();
cv.put(KEY_ITEMMOVEHOLDER, sitemmoveholder);
cv.put(KEY_ROOMHOLDER, sroomholder);
cv.put(KEY_ITEMNAME, sitemname);
cv.put(KEY_ITEMVALUE, sitemvalue);
cv.put(KEY_ITEMWEIGHT, sitemweight);
return ourDatabase.insert(DATABASE_TABLE3, null, cv);
public void updateItems(String sitemmoveholder, String sroomholder, String sitemname, String sitemvalue, String sitemweight)
ContentValues cv = new ContentValues();
cv.put(KEY_ITEMVALUE, sitemvalue);
cv.put(KEY_ITEMWEIGHT, sitemweight);
ourDatabase.update(DATABASE_TABLE3, cv, KEY_ITEMMOVEHOLDER + "='" + sitemmoveholder + "'" + " AND " +
KEY_ROOMHOLDER + "='" + sroomholder + "'" + " AND " + KEY_ITEMNAME + "='" + sitemname + "'", null);
public Cursor getMove()
String[] columns = new String[]KEY_ID1, KEY_MOVENAME;
Cursor c = null;
try
c = ourDatabase.query(DATABASE_TABLE1, columns, null, null, null, null, null);
catch (Exception e)
c.close();
return c;
public String getTotalWeight(String m) throws SQLException
String[] columns = new String[]KEY_ID1, KEY_MOVENAME, KEY_MOVEDATE, KEY_TOTALMOVEWEIGHT;
Cursor c = null;
try
c = ourDatabase.query(DATABASE_TABLE1, columns, KEY_MOVENAME + "= '" + m + "'", null, null, null, null);
if (c != null)
c.moveToFirst();
String totalWeight = c.getString(3);
return totalWeight;
catch (Exception e)
c.close();
return null;
public String getTotalWeightLBS(String m) throws SQLException
String[] columns = new String[]KEY_ID1, KEY_MOVENAME, KEY_MOVEDATE, KEY_TOTALMOVEWEIGHT;
Cursor c = null;
try
c = ourDatabase.query(DATABASE_TABLE1, columns, KEY_MOVENAME + "= '" + m + "'", null, null, null, null);
if (c != null)
c.moveToFirst();
int x = Integer.parseInt(c.getString(3)) * 7;
String totalWeight = "" + x + " lbs";
return totalWeight;
catch (Exception e)
c.close();
return null;
public String getDateMove(String md)
String[] columns = new String[]KEY_ID1, KEY_MOVENAME, KEY_MOVEDATE;
Cursor c = null;try
c = ourDatabase.query(DATABASE_TABLE1, columns, KEY_MOVENAME + "= '" + md + "'", null, null, null, null);
if (c != null)
c.moveToFirst();
String moveDate = c.getString(2);
return moveDate;
catch (Exception e)
c.close();
return null;
public ArrayList<String> loadRooms(String mn) throws SQLException
String[] columns = new String[]KEY_ID2, KEY_ROOMMOVEHOLDER, KEY_ROOM;
ArrayList<String> array = new ArrayList<String>();
Cursor c = null;
try
c = ourDatabase.query(DATABASE_TABLE2, columns,KEY_ROOMMOVEHOLDER + "='" + mn + "'",
null, null, null, null);
int iroom = c.getColumnIndex(KEY_ROOM);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
array.add(c.getString(iroom));
catch (Exception e)
c.close();
return array;
public void deleteMove(String m) throws SQLException
ourDatabase.delete(DATABASE_TABLE1, KEY_MOVENAME + "='" + m + "'", null);
ourDatabase.delete(DATABASE_TABLE2, KEY_ROOMMOVEHOLDER + "='" + m + "'", null);
ourDatabase.delete(DATABASE_TABLE3, KEY_ITEMMOVEHOLDER + "='" + m + "'", null);
ourDatabase.delete(DATABASE_TABLE4, KEY_TODOMOVE + "='" + m + "'", null);
public ArrayList<String> getitems()
String[] columns = new String[]KEY_ID5, KEY_ITEMNAME;
ArrayList<String> items;
items = new ArrayList<String>();
Cursor c = null;
try
c = ourDatabase.query(DATABASE_TABLE5, columns, null, null, null, null, null);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
items.add(c.getString(1));
catch (Exception e)
c.close();
return items;
public ArrayList<String> getitemweight()
String[] columns = new String[]KEY_ID5, KEY_ITEMWEIGHT;
ArrayList<String> items = new ArrayList<String>();
Cursor c = null;
try
c = ourDatabase.query(DATABASE_TABLE5, columns, null, null, null, null, null);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
items.add(c.getString(1));
catch (Exception e)
c.close();
return items;
public ArrayList<String> getitemclass()
String[] columns = new String[]KEY_ID5, KEY_LISTITEMROOM;
ArrayList<String> items = new ArrayList<String>();
Cursor c = null;
try
c = ourDatabase.query(DATABASE_TABLE5, columns, null, null, null, null, null);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
items.add(c.getString(1));
catch (Exception e)
c.close();
return items;
【问题讨论】：
【参考方案1】：getDateMove、getTotalWeightLBS、loadRooms、...中没有关闭光标。
在不再需要光标的地方关闭它。在这些方法中使用try-finally，即使抛出异常，也会保证在finally块中执行代码。
从这里更改方法中的代码：
try
// get data from cursor
catch (Exception e)
c.close();
到这里：
try
// get data from cursor
catch (Exception e)
// exception handling
finally
if(c != null)
c.close();
【讨论】：
等一下，我打错字了，请稍等 该异常是由checkMove 方法引发的，该方法未包含在您的代码中。
如果你已经读完了 Cursor，关闭它 - 就这样。【参考方案2】：
如果一个元素正在实现 AutoCloseable（就像 Cursor.class 所做的那样），我建议执行 try-with-resources，就像描述的 here 一样。
如果你使用 Retrolambda，它有 try-with-resources 向后移植。
所以你的代码：
Cursor cursor = db.query("tableName", columns, null, null, null, null, null);
try
if (cursor.moveToFirst()) return cursor.getString(3);
else return null;
finally
cursor.close();
只会变成：
try (Cursor cursor = db.query("tableName", columns, null, null, null, null, null))
if (cursor.moveToFirst()) return cursor.getString(3);
else return null;
【讨论】：
请注意，此方法需要 API 19 我在 API 11 中使用它，并且在过去几个月有大约 3k 用户时从未遇到过崩溃。 Android Studio 的检查器用“Try-with-resources 需要 API 级别 19（当前最小值为 15）”以红色突出显示 try，但是我进行了测试，它在手机 API 级别 17 上编译和运行良好. 显然 minAPI***.com/questions/20480090/… 虽然它可能适用于某些设备，但不建议这样做。 为什么要在 try 块内打开光标？ @Malachiasz 因为它是最小化局部变量范围的好习惯（有效的 Java 项目 #45）。委托关闭光标也是一个好主意，因为它不容易出错，而且你不能忘记调用.close。【参考方案3】：
在finally 中关闭光标将保证它会被关闭；
public void myfunc()
Cursor c = null;
try
c = ... // Open cursor here
return .... // maybe return something
finally
if(c != null) c.close();
【讨论】：
为什么要在 try 块内打开光标？ try-with-resources 更加优雅【参考方案4】：如果您使用 Kotlin（也可以在 Java 中以稍微不同的方式使用）和 Android 4.1 及更高版本，您可以使用这个：
cursor?.use
//..do stuff
例如，您可以查看here。
如果您想使用 Java，请执行以下操作：
try (Cursor cursor = ...)
// do something
【讨论】：
【参考方案5】：在onStop() 或onDestroy() 活动的方法中关闭您的数据库！
【讨论】：
【参考方案6】：您正在尝试使用
关闭 catch 块内的光标catch (Exception e)
c.close();
但是如果你没有得到任何异常，那么它将如何关闭
所以把它放在 finally 块中
finally
c.close();
【讨论】：
哦，然后在您从查询中获得光标后尝试调用startManagingCursor()。
已经这样做了，一直给出错误接缝的光标来自数据库，而不是来自活动的光标【参考方案7】：
试试这个，
在onStop() 或onDestroy()
检查光标是否为空
@Override
public void onStop()
Cursor cursor;
if(cursor!=null)
cursor.close();
如果没有则关闭光标。
编辑
关闭数据库对象
DatabaseObject db;
if(db!=null)
db.close();
希望对你有帮助。
【讨论】：
哦，我明白了。尝试关闭你的数据库对象以上是关于如何在android中正确关闭光标的主要内容，如果未能解决你的问题，请参考以下文章
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