Databases
StackOverflow2013
Postsdbo
PODatabase | if (c.moveToFirst()) | NPE
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PODatabase | if (c.moveToFirst()) | NPE
    primarykey
    data
    text
    <p>So I've gotten around to making a database and when I'm trying to getAllRecords, the app throws a null pointer.</p> <pre><code>DBAdapter db = new DBAdapter(this); </code></pre> <p>-</p> <pre><code>db.open(); Cursor c = db.getAllRecords(); if (c.moveToFirst()) //&lt;--- NPE { do { DisplayRecord(c); } while (c.moveToNext()); } db.close(); </code></pre> <p>I can't figure out why it's doing this. My insert statement is:</p> <pre><code>db.open(); long id = db.insertRecord("Peanuts"); id = db.insertRecord("Coconuts"); id = db.insertRecord("Almonds"); db.close(); </code></pre> <p>I don't understand why this is returning null</p> <p><strong>Edit:</strong> Entire Database code per request</p> <pre><code>import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; public class DBAdapter { public static final String KEY_ROWID = "id"; public static final String KEY_ITEM = "item"; private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "InventoryDB"; private static final String DATABASE_TABLE = "inventory"; private static final int DATABASE_VERSION = 1; private static final String DATABASE_CREATE = "create table if not exists inventory (id integer primary key autoincrement, " + "item VARCHAR not null);"; private final Context context; private DatabaseHelper DBHelper; private SQLiteDatabase db; public DBAdapter(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(); } } @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 inventory"); onCreate(db); } } //---opens the database--- public DBAdapter open() throws SQLException { db = DBHelper.getWritableDatabase(); return this; } //---closes the database--- public void close() { DBHelper.close(); } //---insert a record into the database--- public long insertRecord(String item) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_ITEM, item); return db.insert(DATABASE_TABLE, null, initialValues); } //---deletes a particular record--- public boolean deleteContact(long rowId) { return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) &gt; 0; } //---retrieves all the records--- public Cursor getAllRecords() { return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_ITEM}, null, null, null, null, null, null); } //---retrieves a particular record--- public Cursor getRecord(long rowId) throws SQLException { Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, KEY_ITEM}, KEY_ROWID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } //---updates a record--- public boolean updateRecord(long rowId, String item) { ContentValues args = new ContentValues(); args.put(KEY_ITEM, item); return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) &gt; 0; } </code></pre> <p>}</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USAdariel Lzinski
    1. USAdariel Lzinski
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. COWhat is the data type of `db`? How is it initialized? The method `getAllRecords()` does not exist in `android.database.sqlite.SQLiteDatabase`.
      singulars
      1. PODatabase | if (c.moveToFirst()) | NPE
      1. USTed Hopp
    2. COdatabase adapter. Check edit..
      singulars
      1. PODatabase | if (c.moveToFirst()) | NPE
      1. USAdariel Lzinski
    3. COThe problem is in `DBAdapter.getAllRecords()`. You'll have to post the code for that for anyone to be able to help you. (`DBAdapter` is not a standard part of Android.)
      singulars
      1. PODatabase | if (c.moveToFirst()) | NPE
      1. USTed Hopp
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload