sqlite

Detecting forgotten SQLite transaction on Android using StrictMode?

由 不羁的心 提交于 2020-01-12 08:06:25
问题 Executing multiple SQL statements without putting them into one transaction is a severe bottleneck (see e.g. http://www.sqlite.org/faq.html#q19). I haven't thoroughly checked how SQLite is configured on Android, but anecdotally I perceived dramatical performance increase within my on app when using transactions in more places. Is it possible to detect instances where one forgets to use transactions using StrictMode? If not, could that be considered for a future release of StrictMode? It might

Detecting forgotten SQLite transaction on Android using StrictMode?

由 谁说我不能喝 提交于 2020-01-12 08:06:22
问题 Executing multiple SQL statements without putting them into one transaction is a severe bottleneck (see e.g. http://www.sqlite.org/faq.html#q19). I haven't thoroughly checked how SQLite is configured on Android, but anecdotally I perceived dramatical performance increase within my on app when using transactions in more places. Is it possible to detect instances where one forgets to use transactions using StrictMode? If not, could that be considered for a future release of StrictMode? It might

Sqlite入门使用及常见问题

由 佐手、 提交于 2020-01-12 06:41:30
下载及启用sqlite SQLite是一款轻型的数据库，占用资源非常的低，处理速度很快，如果想要快速在自己电脑中搭建一个小型数据库，非常推荐使用。 可以在官网下载数据库文件。官网下载地址：https://www.sqlite.org/download.html。 以windows为例：最好下载第三个带.exe的文件，即使电脑是64位也没有关系，64位的电脑能执行32位的应用程序。 下载后解压会发现有三个文件，经常使用的就是第二个.exe文件。 可以发现它非常小，放在电脑想要的位置后，把文件路径添加到环境变量中就能通过CMD调用了。 有一个非常方便的操作就是直接把sqlite.exe文件放到和数据库同一个文件夹中，想要打开数据库的时候，直接双击该文件，然后执行代码。 .open DatabaseName.db 就在文件夹里创建一个名为DatabaseName.db的数据库了。下次要打开该数据库，执行同样的代码就行，注意数据库名称不要打错了，不然会创建一个新的空数据库。 创建表格和数据库查询和其他数据库类似，不再赘述。 sqlite常用命令 查看所有表格 .tables 查看所有表结构 .schema 可以查看该数据库中所有表格的结构，每个字段的数据类型。可以和后文中的.output联合使用，将表结构导出。 查看所有命令 .help 即可查看所有的sqlite命令， 数据库完整性检验

Android ContentProvider calls bursts of setNotificationUri() to CursorAdapter when many rows are inserted with a batch operation

由 人走茶凉 提交于 2020-01-12 04:44:32
问题 I have a custom ContentProvider which manages the access to a SQLite database. To load the content of a database table in a ListFragment , I use the LoaderManager with a CursorLoader and a CursorAdapter : public class MyListFragment extends ListFragment implements LoaderCallbacks<Cursor> { // ... CursorAdapter mAdapter; @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); mAdapter = new CursorAdapter(getActivity(), null, 0);

Idiom to close a cursor

由 十年热恋 提交于 2020-01-12 04:41:46
问题 Which of the following two should I be using to make sure that all the cursors are closed? Cursor c = getCursor(); if(c!=null && c.getCount()>0){ try{ // read values from cursor }catch(..){} finally{ c.close(); } }//end if OR Cursor c = getCursor(); try{ if(c!=null && c.getCount()>0){ // read values from cursor }//end if }catch(..){ }finally{ c.close(); } EDIT: A few questions: 1. Do we need to call close() on a cursor which has count of 0? 2. Because in that case for the first idiom, close()

Idiom to close a cursor

由 断了今生、忘了曾经 提交于 2020-01-12 04:41:10
问题 Which of the following two should I be using to make sure that all the cursors are closed? Cursor c = getCursor(); if(c!=null && c.getCount()>0){ try{ // read values from cursor }catch(..){} finally{ c.close(); } }//end if OR Cursor c = getCursor(); try{ if(c!=null && c.getCount()>0){ // read values from cursor }//end if }catch(..){ }finally{ c.close(); } EDIT: A few questions: 1. Do we need to call close() on a cursor which has count of 0? 2. Because in that case for the first idiom, close()

Android SQLITE 操作工具类

由 一笑奈何 提交于 2020-01-12 04:18:08
首先创建一个类 DatabaseHelper 继承SQLiteOpenHelper帮助类,定义数据库版本，数据库名称，创建表名。 private static final int DATABASE_VERSION = 1; //数据库版本号 private static final String DATABASE_NAME = "Test"; //数据库名称 private static final String HR_B_DEPT = "HR_B_DEPT";//部门 初始化 public DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } 创建表 @Override public void onCreate(SQLiteDatabase db) { String sqldept = "create table HR_B_DEPT(INNERID String PRIMARY KEY ,DEPTCODE text,DEPTNAME text,PARENTID text)"; db.execSQL(sqldept); } 创建一个类 UseDatabase, public class UseDatabase { Context context;

Interacting with external SQLite databases from Android.

由 孤街醉人 提交于 2020-01-12 03:51:07
问题 I'm trying to work with a web service (that I have no control over) that returns a SQLite database when you query it. Is there any way to do this? 回答1: I am working on a project that's doing something similar. I request updates to a database and depending on the volume of updates required, it either sends down an entirely new database or a series of SQL statements. I would strongly suggest keeping the databases on the sdcard if it is available, especially if the size of the databases you're

How to save online data with SharedPreference in Android

由 喜你入骨 提交于 2020-01-11 14:42:29
问题 I want to show 3 fragments in my Activity and load data from json in any fragments ! I need to show website data into Recyclerview with OkHTTP v3 library. I want to show this data for offline, I mean, if user turn off data/wifi show this datas for offline . but i do not want use SQLite Database ! For this idea i use SharedPreference for save data and when disable network show show to offline data from this Preference . I write below codes, but when disable network not show me datas the

How to save online data with SharedPreference in Android

由 独自空忆成欢 提交于 2020-01-11 14:42:17
问题 I want to show 3 fragments in my Activity and load data from json in any fragments ! I need to show website data into Recyclerview with OkHTTP v3 library. I want to show this data for offline, I mean, if user turn off data/wifi show this datas for offline . but i do not want use SQLite Database ! For this idea i use SharedPreference for save data and when disable network show show to offline data from this Preference . I write below codes, but when disable network not show me datas the
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