我有一個關於在Android中的SQLite數據庫表中插入默認值的問題。我有一個DBHandler(顯然)負責創建數據庫,表和執行CRUD查詢。如何在Android SQLite中插入默認值?
但我似乎無法弄清楚,是如何在表中插入默認值。 首先,我試着用下面的方法將在我的DBHandler默認值:
// Write settings to db
public void addSetting(String key, String value) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(SETTING_KEY, key);
values.put(SETTING_VALUE, value);
db.insert(TABLE_APP_SETTINGS, null, values);
db.close();
}
被稱爲用這樣的方法的onCreate():
@Override
public void onCreate(SQLiteDatabase db) {
// creating tables
db.execSQL(DATABASE_CREATE);
db.execSQL(CREATE_TABLE_SETTINGS);
// insert default values
this.addSetting("access_admin_fingers", "2");
}
但由於某些原因,這引起了應用程序崩潰,給我下面的logcat消息:
02-18 09:43:52.050: W/dalvikvm(14297): threadid=1: thread exiting with uncaught exception (group=0x41f3d930)
02-18 09:43:52.060: E/AndroidRuntime(14297): FATAL EXCEPTION: main
02-18 09:43:52.060: E/AndroidRuntime(14297): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.customerratingsystem/com.customerratingsystem.AdminActivity}: java.lang.IllegalStateException: getDatabase called recursively
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.ActivityThread.access$600(ActivityThread.java:141)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.os.Handler.dispatchMessage(Handler.java:99)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.os.Looper.loop(Looper.java:137)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.ActivityThread.main(ActivityThread.java:5041)
02-18 09:43:52.060: E/AndroidRuntime(14297): at java.lang.reflect.Method.invokeNative(Native Method)
02-18 09:43:52.060: E/AndroidRuntime(14297): at java.lang.reflect.Method.invoke(Method.java:511)
02-18 09:43:52.060: E/AndroidRuntime(14297): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:817)
02-18 09:43:52.060: E/AndroidRuntime(14297): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
02-18 09:43:52.060: E/AndroidRuntime(14297): at dalvik.system.NativeStart.main(Native Method)
02-18 09:43:52.060: E/AndroidRuntime(14297): Caused by: java.lang.IllegalStateException: getDatabase called recursively
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:204)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
02-18 09:43:52.060: E/AndroidRuntime(14297): at com.db.DBHandler.addSetting(DBHandler.java:69)
02-18 09:43:52.060: E/AndroidRuntime(14297): at com.db.DBHandler.onCreate(DBHandler.java:51)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:252)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
02-18 09:43:52.060: E/AndroidRuntime(14297): at com.db.DBHandler.getSetting(DBHandler.java:83)
02-18 09:43:52.060: E/AndroidRuntime(14297): at com.customerratingsystem.AdminActivity.onCreate(AdminActivity.java:28)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.Activity.performCreate(Activity.java:5104)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
02-18 09:43:52.060: E/AndroidRuntime(14297): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
然後我試圖將這種「默認值」從我的UI調用addSetting方法像這樣:
db = new DBHandler(getApplicationContext());
db.addSetting("access_admin_fingers", "2");
哪些工作!但我的問題在於:爲什麼我不能在DBHandler中使用這種方法?
此外,什麼prober方式插入默認值在Android SQLite數據庫?
當然!有道理,非常感謝! :) – Langkiller