我尝试获取一些数据库值并将其显示在列表视图中。
这是我的代码:
public class SearchCustomer extends Activity{ private DBCreater dbHelper; private SimpleCursorAdapter dataAdapter; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.search_customer); dbHelper = new DBCreater(this); dbHelper.open(); displayListView(); } private void displayListView(){ Cursor cursor = dbHelper.fetchallcustomerdata(); String[] columns = new String[] { DBCreater.Key_customer_Name, DBCreater.Key_customer_Shop, DBCreater.Key_customer_Location, DBCreater.Key_customer_Phon, DBCreater.Key_customer_Email, DBCreater.Key_customer_Address }; int[] to = new int[]{ R.id.tv_I_name_demo, R.id.tv_I_shop_demo, R.id.tv_I_location_demo, R.id.tv_I_phone_demo, R.id.tv_I_email_demo, R.id.tv_I_address_demo }; final ListView listView = (ListView)findViewById(R.id.lv_I_listofcustomer_searchCustomer); dataAdapter = new SimpleCursorAdapter(this, R.layout.demosearch, cursor, columns, to,0); listView.setAdapter(dataAdapter); listView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> lidstView, View view, int position, long id) { // TODO Auto-generated method stub Cursor cursor =(Cursor)listView.getItemAtPosition(position); //Toast.makeText(cursor.getColumnIndexOrThrow(""), text, duration) String name=cursor.getString(cursor.getColumnIndexOrThrow("customer_name")); Toast.makeText(getApplicationContext(), name, Toast.LENGTH_SHORT).show(); } }); EditText myFilter = (EditText)findViewById(R.id.et_I_filter_searchCustomer); myFilter.addTextChangedListener(new TextWatcher() { @Override public void onTextChanged(CharSequence s, int start, int before, int count) { // TODO Auto-generated method stub dataAdapter.getFilter().filter(s.toString()); } @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { // TODO Auto-generated method stub } @Override public void afterTextChanged(Editable s) { // TODO Auto-generated method stub } }); dataAdapter.setFilterQueryProvider(new FilterQueryProvider() { @Override public Cursor runQuery(CharSequence constraint) { // TODO Auto-generated method stub return dbHelper.fetchcustomerbyname(constraint.toString()); } }); } }
我得到的RuntimeException IllegalArgumentException
IllegalArgumentException
这是错误:
03-11 20:11:24.650:E / AndroidRuntime(887):java.lang.RuntimeException: 无法启动活动 ComponentInfo {com.NIRR.redistributionsystem / com.NIRR.redistributionsystem.SearchCustomer}: java.lang.IllegalArgumentException:列’_id’不存在
这是我的数据库查询:
public Cursor fetchallcustomerdata() { /*Cursor mCursor=ourDatabase.query(DATABASE_TABLE_CUSTOMER,new String[]{ Key_customer_Name,Key_customer_Shop,Key_customer_Location,Key_customer_Phon, Key_customer_Email,Key_customer_Address},null,null,null,null,null,null);*/ String selectQuery = "select customer_name,customer_shop,customer_location,customer_phon,customer_email,customer_address from Customer" ; SQLiteDatabase db = ourHelper.getReadableDatabase(); Cursor mCursor = db.rawQuery(selectQuery, null); if(mCursor != null){ mCursor.moveToFirst(); } return mCursor; }
我使用的sql查询在SQLite db浏览器上运行时会给我正确的查询。我不知道这是什么意思column '_id',因为“不退出”这一行来了
column '_id'
dataAdapter = new SimpleCursorAdapter(this, R.layout.demosearch, cursor, columns, to,0);
请帮我谢谢。
按照文档的CursorAdapter,它的SimpleCursorAdapter一个子类:
CursorAdapter
SimpleCursorAdapter
游标必须包含一个名为“ _id”的列,否则此类将无法工作。
如果您的表已经有一个名为“ _id”的列,则只需将该列包括在查询的投影中(所请求的列)。
String selectQuery = "select _id, customer_name, ... from Customer";
如果您的表中没有“ _id”列,则可以对所有SQLite表默认具有的“行”进行别名(除非明确创建了没有行的列)。
String selectQuery = "select rowid as _id, customer_name, ... from Customer";
即使您不使用原始SQL,也可以执行相同的操作。例如,在query()通话中:
query()
mCursor = db.query("Customer", new String[] {"rowid as _id", "customer_name", ...}, ...);
如果等效于“ _id”,则当然可以为另一列添加别名。不过请注意,Cursor如果您要手动从中检索值,则必须将别名(即“ _id”)与一起使用。
Cursor