[英]Populating Spinner From SQLite Database Android
I'm attempting to make a dynamic drop down that will be filled by a SQLite table. 我正在尝试创建一个由SQLite表填充的动态下拉列表。 I have a Cursor object which I can pull the data I need from.
我有一个Cursor对象,我可以从中提取所需的数据。 I've been able to accomplish loading the values into the drop down with the code below:
我已经能够使用下面的代码将值加载到下拉列表中:
Spinner s = (Spinner) findViewById(R.id.spinner);
ArrayAdapter adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
s.setAdapter(adapter);
try{
Cursor cursor = getAccounts();
int accountnameIndex = cursor.getColumnIndexOrThrow(ACCOUNT_NAME);
if(cursor.moveToFirst()){
do{
adapter.add(cursor.getString(accountnameIndex));
} while(cursor.moveToNext());
}
} finally {
MintLink.close();
}
My problem is that I need the a selection from the drop down to also contain the RowID of the item selected. 我的问题是我需要从下拉列表中选择一个也包含所选项目的RowID。 I need to be able to select one item and have access to the value of that item in the back end.
我需要能够选择一个项目并且可以访问后端中该项目的值。 For example, think of a drop down in HTML.
例如,想一想HTML中的下拉菜单。 Each drop down selection has it's own hidden value that is pulled.
每个下拉选项都有自己的隐藏值。 I need this value to be hidden for me to allow me to know which ID they choose.
我需要隐藏此值才能让我知道他们选择了哪个ID。
This is an old question but the first one I found when figuring out this issue. 这是一个老问题,但是我在找出这个问题时找到的第一个问题。 Here is a detailed explanation with full source which may cut some legwork.
这里有一个完整的来源的详细解释,可能削减一些腿部工作。
The answer is indeed to use a SimpleCursorAdapter which handles a list of strings but also has special handling for a matched ID field that gets returned when a row is selected. 答案确实是使用SimpleCursorAdapter处理字符串列表,但也对匹配的ID字段进行特殊处理,该字段在选择行时返回。 The key to making this work is to know the two following obscure bits of information:
完成这项工作的关键是要知道以下两个模糊的信息:
1) When creating the cursor make sure the query returns a field titled "_id". 1)创建光标时,请确保查询返回标题为“_id”的字段。 This field need not be displayed anywhere but it's value will be passed back when a list item is selected.
此字段无需显示在任何位置,但在选择列表项时它的值将被传回。
2) When creating a SimpleCursorAdapter you need to supply the TextView layout IDs where the row text will be placed. 2)创建SimpleCursorAdapter时,需要提供将放置行文本的TextView布局ID。 If using the android supplied layout android.R.layout.simple_spinner_item the text id you need to use is android.R.id.text1.
如果使用android提供的布局android.R.layout.simple_spinner_item,则需要使用的文本ID是android.R.id.text1。
Main.xml main.xml中
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Spinner
android:id="@+id/spinner1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
></Spinner>
</RelativeLayout>
Activity code: 活动代码:
public class TesterActivity extends Activity {
public Context mContext;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// just for this example:
// create database table with an id field and a text field and add some data
class MyDBHelper extends SQLiteOpenHelper {
public MyDBHelper(Context context) {
super(context, "someDB", null, 2);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE someTable (someIDF INTEGER, someTextF TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS someTable");
onCreate(db);
db.execSQL("INSERT INTO someTable (someIDF, someTextF) VALUES (54, 'Some text')");
db.execSQL("INSERT INTO someTable (someIDF, someTextF) VALUES (99, 'Some more text')");
db.execSQL("INSERT INTO someTable (someIDF, someTextF) VALUES (173, 'Even more text')");
}
}
SQLiteDatabase db = new MyDBHelper(this).getWritableDatabase();
// get a cursor from the database with an "_id" field
Cursor c = db.rawQuery("SELECT someIDF AS _id, someTextF FROM someTable", null);
// make an adapter from the cursor
String[] from = new String[] {"someTextF"};
int[] to = new int[] {android.R.id.text1};
SimpleCursorAdapter sca = new SimpleCursorAdapter(this, android.R.layout.simple_spinner_item, c, from, to);
// set layout for activated adapter
sca.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// get xml file spinner and set adapter
Spinner spin = (Spinner) this.findViewById(R.id.spinner1);
spin.setAdapter(sca);
// set spinner listener to display the selected item id
mContext = this;
spin.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View view, int position, long id){
Toast.makeText(mContext, "Selected ID=" + id, Toast.LENGTH_LONG).show();
}
public void onNothingSelected(AdapterView<?> parent) {}
});
}
}
尝试使用SimpleCursorAdapter
而不是手动将所有数据复制到ArrayAdapter
。
Here's another answer with loaders and cursors. 这是加载器和游标的另一个答案。
In the activity/fragment creation (said fragment/activity must implement LoaderManager.LoaderCallbacks<Cursor>
): 在活动/片段创建中(所述片段/活动必须实现
LoaderManager.LoaderCallbacks<Cursor>
):
final Spinner spinner = (Spinner) findViewById(R.id.spinner);
mAdapter = new MyCursorAdapter(getActivity());
spinner.setAdapter(mAdapter);
getLoaderManager().initLoader(SOME_INT_CONSTANT, null, this);
In your activity/fragment: 在您的活动/片段中:
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
return new MyCursorLoader(getActivity(), args);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
mAdapter.swapCursor(data);
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
mAdapter.swapCursor(null);
}
Here's the cursor adapter: 这是光标适配器:
class MyCursorAdapter extends CursorAdapter {
class ViewsHolder {
TextView text1, text2;
}
public MyCursorAdapter(Context context, Bundle args) {
super(context, null, false);
// do something with args
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
View v = LayoutInflater.from(context).inflate(R.layout.your_item_layout, parent, false);
ViewsHolder holder = new ViewsHolder();
holder.text1 = (TextView) v.findViewById(R.id.text1);
holder.text2 = (TextView) v.findViewById(R.id.text2);
v.setTag(holder);
return v;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
ViewsHolder holder = (ViewsHolder) view.getTag();
String text1 = cursor.getString(cursor.getColumnIndex(KEY_TEXT1));
String text2 = cursor.getString(cursor.getColumnIndex(KEY_TEXT2));
holder.text1.setText(text1);
holder.text2.setText(text2);
}
}
Here's the cursor loader: 这是光标加载器:
public class MyCursorLoader extends CursorLoader {
private final YourSQLiteDbAdapter mHelper;
public MyCursorLoader(Context context) {
super(context);
mHelper = new YourSQLiteDbAdapter(context);
mHelper.openReadOnly();
}
@Override
public Cursor loadInBackground() {
return mHelper.selectYourDataAsACursor();
}
@Override
protected void onStopLoading() {
super.onStopLoading();
mHelper.close();
}
}
Using this you get: 使用这个你得到:
Example of data binding can be found here. 可以在此处找到数据绑定的示例。
http://developer.android.com/guide/topics/ui/binding.html http://developer.android.com/guide/topics/ui/binding.html
check "Filling the Layout with Data" section for usage of SimpleCursorAdapter
选中“使用数据填充布局”部分以使用
SimpleCursorAdapter
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