我正在开发一个Android应用程序,需要创建一个数据库。
我已经扩展了SQLiteOpenHelper
类,但它对我没有起作用。有人能告诉我如何通过它或其他语法或代码来创建数据库吗?请提供一些好的教程或示例来学习在应用程序中创建和实现数据库。
这是我尝试遵循vogella.de
教程时的日志文件:
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): FATAL EXCEPTION: main
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{de.vogella.android.todos.database/de.vogella.android.todos.database.TodoDatabaseHelper}: java.lang.InstantiationException: de.vogella.android.todos.database.TodoDatabaseHelper
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1544)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1638)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:928)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.os.Handler.dispatchMessage(Handler.java:99)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.os.Looper.loop(Looper.java:123)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.app.ActivityThread.main(ActivityThread.java:3647)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at java.lang.reflect.Method.invokeNative(Native Method)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at java.lang.reflect.Method.invoke(Method.java:507)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at dalvik.system.NativeStart.main(Native Method)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): Caused by: java.lang.InstantiationException: de.vogella.android.todos.database.TodoDatabaseHelper
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at java.lang.Class.newInstanceImpl(Native Method)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at java.lang.Class.newInstance(Class.java:1409)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1536)
06-17 13:20:11.883: ERROR/AndroidRuntime(1474): ... 11 more
06-17 13:20:12.004: WARN/ActivityManager(68): Force finishing activity de.vogella.android.todos.database/.TodoDatabaseHelper