Android Eclipse 无法读取我的 SQLite 数据库

Question

我的 SQLite 数据库总是有问题，有人帮忙解决吗？

这是我的DatabaseHelper.java

private static final String     DB_NAME     = "msekolah";
private static final int        DB_VER      = 1;

private static final String  SD_DATA  = "sd_data";
 public static final String  COL_ID  = "_rowid";
 public static final String  COL_NAMA = "namasek";
 public static final String  COL_ALAMAT = "address";
 public static final String  COL_KELURAHAN = "kelu";
 public static final String  COL_LATI = "lat";
 public static final String  COL_LONG = "lon";

private static DatabaseHelper   dbInstance;
private static SQLiteDatabase   db;

private DatabaseHelper(Context context)
{
    super(context, DB_NAME, null, DB_VER);
}

public static DatabaseHelper getInstance(Context context)
{
    if (dbInstance == null)
    {
        dbInstance = new DatabaseHelper(context);

    }
    return dbInstance;
}

@Override
public synchronized void close()
{
    super.close();
    if (dbInstance != null)
    {
        dbInstance.close();
    }
}

public List<Kamus> getAllKamus()
{
    List<Kamus> lisKamus = new ArrayList<Kamus>();

    Cursor cursor = db.query(SD_DATA, new String[] { 
            COL_ID, COL_NAMA, COL_ALAMAT, COL_KELURAHAN, COL_LATI, COL_LONG }, 
            COL_ID + "=" + "_rowid",
            null, null, null, null);
          if (cursor.getCount() >= 1)
    {
        cursor.moveToFirst();

        do
        {
            Kamus kamus = new Kamus();
            kamus.setLongitude(cursor.getString(cursor.getColumnIndexOrThrow(COL_LONG)));
            kamus.setLatitude(cursor.getString(cursor.getColumnIndexOrThrow(COL_LATI)));
            kamus.setKelurahan(cursor.getString(cursor.getColumnIndexOrThrow(COL_KELURAHAN)));
            kamus.setAlamat(cursor.getString(cursor.getColumnIndexOrThrow(COL_ALAMAT)));
            kamus.setNamaSekolah(cursor.getString(cursor.getColumnIndexOrThrow(COL_NAMA)));
            lisKamus.add(kamus);

        } while (cursor.moveToNext());
    }
    return lisKamus;

}

public Cursor getBukuByJudul(String query)
{
    Cursor cursor = null;

    if (TextUtils.isEmpty(query))
    {
        cursor = db.query(SD_DATA, new String[] { COL_ID, COL_ID,
                COL_NAMA, COL_ALAMAT, COL_KELURAHAN, COL_LATI, COL_LONG }, null, null, null, null, COL_LONG);
    } else
    {
        cursor = db.query(SD_DATA, new String[] { COL_ID, COL_NAMA, COL_ALAMAT, COL_KELURAHAN, COL_LATI, COL_LONG }, COL_LONG + " like '" + query + "%'",
                null, null, null, null);
    }
    return cursor;
}

这是我的MainActivity.java

@Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv = (ListView) findViewById(R.id.lv_data);
        lv.setEmptyView(findViewById(R.id.empty));
        search = (EditText) findViewById(R.id.search);

        dbHelper = DatabaseHelper.getInstance(this);

        setData();

        search.addTextChangedListener(this);
        lv.setOnItemClickListener(this);
    }

    private void setData()
    {
        listKamus = dbHelper.getAllKamus();

        adapter = new ArrayAdapter<Kamus>(this,
                android.R.layout.simple_expandable_list_item_1, listKamus);
        lv.setAdapter(adapter);

    }

    @Override
    public void afterTextChanged(Editable arg0)
    {
    }

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
            int arg3)
    {
    }

    @Override
    public void onTextChanged(CharSequence s, int arg1, int arg2, int arg3)
    {
        adapter.getFilter().filter(s.toString());
    }

    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int position,
            long id)
    {
        // TODO Auto-generated method stub
        Bundle b = new Bundle();
        b.putString("lon", adapter.getItem(position).getLongitude());
        b.putString("lat", adapter.getItem(position).getLatitude());
        b.putString("kelu", adapter.getItem(position).getKelurahan());
        b.putString("address", adapter.getItem(position).getAlamat());
        b.putString("namasek", adapter.getItem(position).getNamaSekolah());

        Intent i = new Intent(this, ArtiActivity.class);
        i.putExtras(b);
        startActivity(i);

    }

}

我已经厌倦了在 Logcat 上找到问题 因为模拟器无法在资产中读取我的数据库 sqlite 请帮忙..

04-12 18:54:45.216：E/AndroidRuntime(275)：致命异常：主要 04-12 18：54：45.216：E/AndroidRuntime（275）：java.lang.RuntimeException： 无法开始活动 组件信息{id.nuhun.lbssekolah/id.nuhun.lbssekolah.MainActivity}： java.lang.NullPointerException 04-12 18:54:45.216: E/AndroidRuntime(275)：在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 04-12 18:54:45.216: E/AndroidRuntime(275): 在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 04-12 18:54:45.216: E/AndroidRuntime(275): 在 android.app.ActivityThread.access$2300(ActivityThread.java:125) 04-12 18：54：45.216：E/AndroidRuntime（275）：在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 04-12 18:54:45.216: E/AndroidRuntime(275): 在 android.os.Handler.dispatchMessage(Handler.java:99) 04-12 18：54：45.216：E/AndroidRuntime（275）：在 android.os.Looper.loop(Looper.java:123) 04-12 18:54:45.216: E/AndroidRuntime(275)：在 android.app.ActivityThread.main(ActivityThread.java:4627) 04-12 18：54：45.216：E/AndroidRuntime（275）：在 java.lang.reflect.Method.invokeNative(Native Method) 04-12 18：54：45.216：E/AndroidRuntime（275）：在 java.lang.reflect.Method.invoke(Method.java:521) 04-12 18:54:45.216: E/AndroidRuntime(275)：在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 04-12 18:54:45.216: E/AndroidRuntime(275): 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 04-12 18：54：45.216：E/AndroidRuntime（275）：在 dalvik.system.NativeStart.main（本机方法）04-12 18:54:45.216： E/AndroidRuntime(275)：引起：java.lang.NullPointerException 04-12 18：54：45.216：E/AndroidRuntime（275）：在 id.nuhun.lbssekolah.DatabaseHelper.getAllKamus（DatabaseHelper.java:58） 04-12 18:54:45.216: E/AndroidRuntime(275): 在 id.nuhun.lbssekolah.MainActivity.setData(MainActivity.java:47) 04-12 18：54：45.216：E/AndroidRuntime（275）：在 id.nuhun.lbssekolah.MainActivity.onCreate(MainActivity.java:39) 04-12 18：54：45.216：E/AndroidRuntime（275）：在 android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 04-12 18:54:45.216: E/AndroidRuntime(275): 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 04-12 18:54:45.216: E/AndroidRuntime(275): ... 11 更多

Answer 1

在您的getAllKamus() 中，您需要在调用query() 等方法之前初始化您的db 变量：

db = dbInstance.getReadableDatabase();