异常如下
java.lang.RuntimeException: cannot find implementation for com.snowman.myapplication.UserDatabase. UserDatabase_Impl does not exist
com.snowman.myapplication.UserDatabase. UserDatabase_Impl does ...
有时公司不让使用三方<em>数据库</em><em>框架</em>，自己又不想一遍一遍的<em>写</em>增删改查。于是出于懒惰，就基于反射加注解，<em>写</em>了一个简单的<em>数据库</em><em>框架</em>。一 、先来看看使用。1） 首相要对要进行增删改查的数据对象进行注解配置，如下以Book类为例：@Table(name="booktwo")
public class Book {
@PrimaryKey
@Column(name="b_id")
public Stri...
cannot find implementation for com.im.room.AppDatabase. AppDatabase_Impl does not exist
@Database(entities = {UserBean.class, ContactBean.class, AttentionUser.class, LabelBean.class}, version = 1)
pu...
Android Studio
SugarORM简介要说SugarORM之前不得不说ORM。ORM（Object-Relational Mapping）即对象关系映射模式，是Java开发中常用的技术。它的作用是在关系型<em>数据库</em>和业务实体对象之间作一个映射，这样，我们在具体的<em>操作</em>业务对象的时候，就不需要再去和复杂的<em>SQL</em>语句打交道，只需简单的<em>操作</em>对象的属性和方法。因为Android开发也是用Java语言
Android开发——<em>数据库</em><em>框架</em>Suger遇到的大坑（Gson和Suger的复用Bean请见“大坑三”）大坑一自己<em>写</em>了一个Demo按照官网以及GitHub上Suger的使用步骤完整走下来，Demo闪退，以插入数据为例 User user = new User("liao","123");
user.setUserName("liao");
user.setPassWo
编译错误
解 ： Entuty 加 getter & setter
Schema 错误提示
Warning： //此时build是成功的。
Error:(13, 17) 警告: Schema export directory is not provided to the annotation processor so we cannot export the schema. ...
09-19 11:25:32.349: E/<em>SQL</em>iteLog(28075): (1) no such table: classlist
09-19 11:25:32.358: D/AndroidRuntime(28075): Shutting down VM
09-19 11:25:32.358: W/dalvikvm(28075): threadid=1: thread exiting with uncaught exception (group=0xb4ea3288)
09-19 11:25:32.379: E/AndroidRuntime(28075): FATAL EXCEPTION: main
09-19 11:25:32.379: E/AndroidRuntime(28075): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kakabuli.phonesafe/com.kakabuli.phonesafe.CommonNumberActivity}: <em>android</em>.database.sqlite.<em>SQL</em>iteException: no such table: classlist (code 1): , while compiling: select count(*) from classlist
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.ActivityThread.access$600(ActivityThread.java:130)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.os.Handler.dispatchMessage(Handler.java:99)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.os.Looper.loop(Looper.java:137)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.ActivityThread.main(ActivityThread.java:4745)
09-19 11:25:32.379: E/AndroidRuntime(28075): at java.lang.reflect.Method.invokeNative(Native Method)
09-19 11:25:32.379: E/AndroidRuntime(28075): at java.lang.reflect.Method.invoke(Method.java:511)
09-19 11:25:32.379: E/AndroidRuntime(28075): at com.<em>android</em>.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-19 11:25:32.379: E/AndroidRuntime(28075): at com.<em>android</em>.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-19 11:25:32.379: E/AndroidRuntime(28075): at dalvik.system.NativeStart.main(Native Method)
09-19 11:25:32.379: E/AndroidRuntime(28075): Caused by: <em>android</em>.database.sqlite.<em>SQL</em>iteException: no such table: classlist (code 1): , while compiling: select count(*) from classlist
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteConnection.nativePrepareStatement(Native Method)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteConnection.acquirePreparedStatement(<em>SQL</em>iteConnection.java:882)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteConnection.prepare(<em>SQL</em>iteConnection.java:493)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteSession.prepare(<em>SQL</em>iteSession.java:588)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteProgram.(<em>SQL</em>iteProgram.java:58)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteQuery.(<em>SQL</em>iteQuery.java:37)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteDirectCursorDriver.query(<em>SQL</em>iteDirectCursorDriver.java:44)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteDatabase.rawQueryWithFactory(<em>SQL</em>iteDatabase.java:1314)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.database.sqlite.<em>SQL</em>iteDatabase.rawQuery(<em>SQL</em>iteDatabase.java:1253)
09-19 11:25:32.379: E/AndroidRuntime(28075): at com.kakabuli.phonesafe.db.dao.CommonNumberDao.getGroupCount(CommonNumberDao.java:23)
09-19 11:25:32.379: E/AndroidRuntime(28075): at com.kakabuli.phonesafe.CommonNumberActivity$CommonNumberAdapter.getGroupCount(CommonNumberActivity.java:63)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.widget.ExpandableListConnector.getCount(ExpandableListConnector.java:397)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.widget.ListView.setAdapter(ListView.java:460)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.widget.ExpandableListView.setAdapter(ExpandableListView.java:470)
09-19 11:25:32.379: E/AndroidRuntime(28075): at com.kakabuli.phonesafe.CommonNumberActivity.onCreate(CommonNumberActivity.java:39)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.Activity.performCreate(Activity.java:5008)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
09-19 11:25:32.379: E/AndroidRuntime(28075): at <em>android</em>.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
线程A打开数据，正在使用<em>数据库</em>，这时cpu片段分到线程B，线程A挂起。线程B进入执行获取打开db时没有问题，线程B进行<em>操作</em>，在片段时间内数据<em>操作</em>完成，最后关闭<em>数据库</em>database.close()。线程B执行结束，线程A执行，插入数据或者其他<em>操作</em>。。。我靠，怎么<em>数据库</em>关闭了呢，然后抛出java.lang.IllegalStateException: attempt to re-open an already-closed object异常。
