我正在尝试通过使用游标从 SQLite 获取数据来填充列表视图。但是即使光标有预期的行，列表视图中也不会显示任何数据。
这是代码：
public class ShowUsers extends Activity {
UserDBAdapter db;
@Override
protected void onCreate(Bundle savedInstanceState) {
try {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_profile);
db = new UserDBAdapter(getApplicationContext());
db.open();
populateListViewFromDB();
} catch (Exception e) {
Log.e("ERROR", "Error occured: " + e.toString());
e.printStackTrace();
}
}
@SuppressWarnings("deprecation")
private void populateListViewFromDB() {
Cursor cursor = db.getAllRecords();
startManagingCursor(cursor);
Log.i("MyApp", "Total users: " + cursor.getCount());
Toast.makeText(getApplicationContext(),
"Number of rows: " + cursor.getCount(), Toast.LENGTH_LONG)
.show();
String[] databaseColumnNames = new String[] { UserDBAdapter.KEY_NAME };
int[] toViewIDs = new int[] { R.id.textViewName };
SimpleCursorAdapter myCursordapter = new SimpleCursorAdapter(this,
R.layout.users_layout, cursor, databaseColumnNames, toViewIDs);
ListView list = (ListView) findViewById(R.id.listViewFromDB);
list.setAdapter(myCursordapter);
}
@Override
protected void onDestroy() {
super.onDestroy();
db.close();
}
}
XML 文件：activity_user_profile.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/listViewFromDB"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:divider="#0000CC"
android:dividerHeight="0.1dp" >
</ListView>
</LinearLayout>
用户布局.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:id="@+id/textViewName"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="25dp"
android:textColor="#0000FF"
android:text="TextView" />
</LinearLayout>
UserDBAdapeter 文件
public class UserDBAdapter {
public static final String KEY_USERID = "id";
public static final String KEY_NAME = "name";
public static final String KEY_BIRTHATE = "birthdate";
public static final String KEY_PUBAGE = "pubage";
public static final String KEY_PASSWORD = "password";
private static final String TAG = "UserDBAdapter";
private static final String DATABASE_NAME = "UserDB";
private static final String DATABASE_TABLE = "Users";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE = "create table if not exists "
+ DATABASE_TABLE
+ " (id integer primary key autoincrement, "
+ "name VARCHAR not null, birthdate date, pubage number, password VARCHAR );";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public UserDBAdapter(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 contacts");
onCreate(db);
}
}
// ---opens the database---
public UserDBAdapter 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 name, String password, String birthdate,
int pubage) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_NAME, name);
initialValues.put(KEY_BIRTHATE, birthdate);
initialValues.put(KEY_PUBAGE, pubage);
initialValues.put(KEY_PASSWORD, password);
return db.insert(DATABASE_TABLE, null, initialValues);
}
// ---deletes a particular record---
public boolean deleteUser(long userId) {
return db.delete(DATABASE_TABLE, KEY_USERID + "=" + userId, null) > 0;
}
// ---retrieves all the records---
public Cursor getAllRecords() {
return db.query(DATABASE_TABLE, new String[] { KEY_USERID, KEY_NAME,
KEY_BIRTHATE, KEY_PUBAGE, KEY_PASSWORD }, null, null, null,
null, null);
}
// ---retrieves a particular record---
public Cursor getRecord(long userId) throws SQLException {
Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {
KEY_USERID, KEY_NAME, KEY_BIRTHATE, KEY_PUBAGE, KEY_PASSWORD },
KEY_USERID + "=" + userId, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
// ---updates a record---
public boolean updateRecord(long userId, String name, String birthdate,
int pubage, String password) {
ContentValues args = new ContentValues();
args.put(KEY_NAME, name);
args.put(KEY_BIRTHATE, birthdate);
args.put(KEY_PUBAGE, pubage);
args.put(KEY_PASSWORD, password);
return db.update(DATABASE_TABLE, args, KEY_USERID + "=" + userId, null) > 0;
}
}
我能够成功地将数据从另一个活动插入到表中，并且能够从该活动中读取，但无法在列表视图中显示。请让我知道这里添加的代码在哪里以及有什么问题。