Java 如何在android中为我的应用程序创建本地数据库
我想在sqlite中为我的android应用程序创建一个简单的数据库。我只想将我的值添加到表中 这是我的代码,但这不适用于我,因为该表未在DDMS中显示Java 如何在android中为我的应用程序创建本地数据库,java,android,sqlite,Java,Android,Sqlite,我想在sqlite中为我的android应用程序创建一个简单的数据库。我只想将我的值添加到表中 这是我的代码,但这不适用于我,因为该表未在DDMS中显示 public class QuickSubmitContext extends SQLiteOpenHelper { private static final int DATABASE_VERSION = 1; private static final String DATABASE_NAME = "submitManager"
public class QuickSubmitContext extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "submitManager";
private static final String TABLE_CONTACTS = "submit";
private static final String KEY_ID = "id";
private static final String KEY_PH_NO = "phone_number";
private static final String KEY_DNCA = "donotca";
private static final String KEY_CA = "callagain";
private static final String KEY_NOTE = "note";
public QuickSubmitContext(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_PH_NO + " TEXT,"
+ KEY_DNCA + " TEXT," + KEY_CA + " TEXT," + KEY_NOTE + " TEXT" + ")";
db.execSQL(CREATE_CONTACTS_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
// Create tables again
onCreate(db);
}
}
Logcat
10-21 04:39:00.230: E/AndroidRuntime(835): FATAL EXCEPTION: main
10-21 04:39:00.230: E/AndroidRuntime(835): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.aspeage.quikw/com.aspeage.quikw.FragmentLayout}: java.lang.NullPointerException
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.os.Handler.dispatchMessage(Handler.java:99)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.os.Looper.loop(Looper.java:137)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.ActivityThread.main(ActivityThread.java:5041)
10-21 04:39:00.230: E/AndroidRuntime(835): at java.lang.reflect.Method.invokeNative(Native Method)
10-21 04:39:00.230: E/AndroidRuntime(835): at java.lang.reflect.Method.invoke(Method.java:511)
10-21 04:39:00.230: E/AndroidRuntime(835): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-21 04:39:00.230: E/AndroidRuntime(835): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-21 04:39:00.230: E/AndroidRuntime(835): at dalvik.system.NativeStart.main(Native Method)
10-21 04:39:00.230: E/AndroidRuntime(835): Caused by: java.lang.NullPointerException
10-21 04:39:00.230: E/AndroidRuntime(835): at com.aspeage.quikw.FragmentLayout.onCreate(FragmentLayout.java:79)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.Activity.performCreate(Activity.java:5104)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
10-21 04:39:00.230: E/AndroidRuntime(835): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
10-21 04:39:00.230: E/AndroidRuntime(835): ... 11 more
10-21 04:39:07.090: I/Process(835): Sending signal. PID: 835 SIG: 9
10-21 04:39:13.050: E/Trace(866): error opening trace file: No such file or directory (2)
创建新SQLite数据库的推荐方法是创建
SQLiteOpenHelper
的子类,并重写onCreate()
方法,在该方法中,您可以执行SQLite命令在数据库中创建表。例如:
public class DictionaryOpenHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 2;
private static final String DICTIONARY_TABLE_NAME = "dictionary";
private static final String DICTIONARY_TABLE_CREATE =
"CREATE TABLE " + DICTIONARY_TABLE_NAME + " (" +
KEY_WORD + " TEXT, " +
KEY_DEFINITION + " TEXT);";
DictionaryOpenHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DICTIONARY_TABLE_CREATE);
}
}
这里有一些说明 请看这篇教程:@FaroukTouzi我看到了那个链接,也创建了它,但我有一个问题,因为我的数据库表没有显示在我的日志中到底是什么错误?请出示您的日志。@FaroukTouzi请检查我用代码更新我的问题请再次检查我修改了我的日志question@Shekhar在onCreate()中放入一些日志以确保数据库已创建。