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我想知道为什么我不能打开我的应用程序。另外，我正在尝试从SQLite数据库中检索数据并插入微调器。

LogCat 说：

08-06 09:37:41.262: I/dalvikvm(532): threadid=3: reacting to signal 3
08-06 09:37:41.343: I/dalvikvm(532): Wrote stack traces to '/data/anr/traces.txt'
08-06 09:37:41.643: D/gralloc_goldfish(532): Emulator without GPU emulation detected.
08-06 09:37:41.773: I/dalvikvm(532): threadid=3: reacting to signal 3
08-06 09:37:41.793: I/dalvikvm(532): Wrote stack traces to '/data/anr/traces.txt'
08-06 09:37:43.293: D/AndroidRuntime(532): Shutting down VM
08-06 09:37:43.303: W/dalvikvm(532): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
08-06 09:37:43.312: E/AndroidRuntime(532): FATAL EXCEPTION: main
08-06 09:37:43.312: E/AndroidRuntime(532): java.lang.RuntimeException: Unable to start activity ComponentInfo{main.page/main.page.PersonalInfo}: java.lang.NullPointerException
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.os.Handler.dispatchMessage(Handler.java:99)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.os.Looper.loop(Looper.java:137)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.ActivityThread.main(ActivityThread.java:4424)
08-06 09:37:43.312: E/AndroidRuntime(532):  at java.lang.reflect.Method.invokeNative(Native Method)
08-06 09:37:43.312: E/AndroidRuntime(532):  at java.lang.reflect.Method.invoke(Method.java:511)
08-06 09:37:43.312: E/AndroidRuntime(532):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
08-06 09:37:43.312: E/AndroidRuntime(532):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
08-06 09:37:43.312: E/AndroidRuntime(532):  at dalvik.system.NativeStart.main(Native Method)
08-06 09:37:43.312: E/AndroidRuntime(532): Caused by: java.lang.NullPointerException
08-06 09:37:43.312: E/AndroidRuntime(532):  at main.page.InfoDBAdapter.getAllContacts(InfoDBAdapter.java:113)
08-06 09:37:43.312: E/AndroidRuntime(532):  at main.page.PersonalInfo.onCreate(PersonalInfo.java:41)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.Activity.performCreate(Activity.java:4465)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
08-06 09:37:43.312: E/AndroidRuntime(532):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
08-06 09:37:43.312: E/AndroidRuntime(532):  ... 11 more
08-06 09:37:43.694: I/dalvikvm(532): threadid=3: reacting to signal 3
08-06 09:37:43.713: I/dalvikvm(532): Wrote stack traces to '/data/anr/traces.txt'
08-06 09:37:43.923: I/dalvikvm(532): threadid=3: reacting to signal 3
08-06 09:37:43.933: I/dalvikvm(532): Wrote stack traces to '/data/anr/traces.txt'

下面是从数据库中检索数据并放入微调器的代码。

@Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.info);

        Cursor c = infoDB.getAllContacts();
        startManagingCursor(c);

        //Create an array to specify which fields want to display
        String[] from = new String[] {"name"};

        //Create an array of the display item want to bind our data to
        int[] to = new int[] {R.id.fName};

        SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, android.R.layout.simple_spinner_item, c, from, to);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        nameSpinner.setAdapter(adapter);

        nameSpinner = (Spinner) findViewById(R.id.nameSpinner);

哦，是的，在我输入代码（上面的那个）之前，我可以打开应用程序。但是在我输入代码后，我无法打开应用程序。我不确定这是否与代码有关。

下面是 DBAdapter 类：

public static final String KEY_ROWID = "_id";
    public static final String KEY_NAME = "name";
    public static final String KEY_DATE = "date";
    public static final String KEY_TYPE = "type";
    public static final String KEY_LIKES = "likes";
    public static final String KEY_DISLIKES = "dislikes";

    private static final String TAG = "InfoDBAdapter";

    private static final String DATABASE_NAME = "friendsDB";
    private static final String DATABASE_TABLE = "friends_info";
    private static final int DATABASE_VERSION = 2;

    private static final String DATABASE_CREATE = "create table friends_info(name_id integer primary key autoincrement, "
            + "name text not null, date text not null, type text not null, likes text not null, dislikes text not null);";

    private final Context context;

    private DatabaseHelper DBHelper;
    private SQLiteDatabase db;

    public InfoDBAdapter(Context ctx)
    {
        this.context = ctx;
        DBHelper = new DatabaseHelper(context);
    }

    private static class DatabaseHelper extends SQLiteOpenHelper
    {
        DatabaseHelper(Context context)
        {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db)
        {
            try
            {
                db.execSQL(DATABASE_CREATE);
            } catch (SQLException e)
            {
                e.printStackTrace();
            }
        }// end onCreate()

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
        {
            Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                    + newVersion + ", which will destroy all old data");
            db.execSQL("DROP TABLE IF EXISTS friends_info");
            onCreate(db);
        }// end onUpgrade()

    }// end DatabaseHelper

        public InfoDBAdapter open() throws SQLException
        {
            db = DBHelper.getWritableDatabase();
            return this;
        }// end open()

        public void close()
        {
            DBHelper.close();
        }// end close()

        public long insertContact(String name, String date, String type, String likes, String dislikes)
        {
            ContentValues initialValues = new ContentValues();
            initialValues.put(KEY_NAME, name);
            initialValues.put(KEY_DATE, date);
            initialValues.put(KEY_TYPE, type);
            initialValues.put(KEY_LIKES, likes);
            initialValues.put(KEY_DISLIKES, dislikes);
            return db.insert(DATABASE_TABLE, null, initialValues);
        }// end insertContact()

        public boolean deleteContact(long rowId)
        {
            return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
        }// end deleteContact()

        public Cursor getAllContacts()
        {
            return db.query(DATABASE_TABLE, new String[] 
                    { KEY_ROWID, KEY_NAME, KEY_DATE, KEY_TYPE, KEY_LIKES, KEY_DISLIKES }, null, null, null, null, null);
        }// end getAllContacts()

        public Cursor getContact(long rowId) throws SQLException
        {
            Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {
                    KEY_ROWID, KEY_NAME, KEY_DATE, KEY_TYPE, KEY_LIKES, KEY_DISLIKES }, KEY_ROWID + "=" + rowId,
                    null, null, null, null, null);
            if (mCursor != null)
            {
                mCursor.moveToFirst();
            }
            return mCursor;
        }// end getContact()

        public boolean updateContact(long rowId, String name, String date, String type, String likes, String dislikes)
        {
            ContentValues args = new ContentValues();
            args.put(KEY_NAME, name);
            args.put(KEY_DATE, date);
            args.put(KEY_TYPE, type);
            args.put(KEY_LIKES, likes);
            args.put(KEY_DISLIKES, dislikes);
            return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
        }// end updateContact()

我感谢提供的任何帮助。哦，如果有人知道从数据库中检索数据并放入微调器的其他方法，我将不胜感激。
谢谢 =)

4

2 回答 2

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看起来你忘了打开你DataBase的操作和你的db referenceisnull和 throwing NullPointerException。尝试调用以下行 -

infoDB = new InfoDBAdapter(mContext);
infoDB.open();
Cursor c = infoDB.getAllContacts();
于 2012-08-06T02:16:24.823 回答
0

InfoDb似乎是null。你是如何初始化它的？

您需要先open()访问数据库，然后才能使用它。

于 2012-08-06T02:24:06.860 回答