android - SPINNER 中是否有任何方法可以选择一个项目并显示另一个相关的值？

Question

我有一个带有“Customer”和“CustomerId”列的表的 SQLite 数据库。

例如：客户：John Doe 客户 ID：84746464

我用“客户”中的数据为微调器充气。当 usr 选择 John Doe 时，我需要在微调器“84746464”中显示。

在android中有没有办法做到这一点？

谢谢！

标签： androidandroid-sqlitespinnerandroid-spinner

Answer 1

在android中有没有办法做到这一点？

是的，当然，这是一个在 Spinner 中同时显示 CustomerId 和 Customer 的示例：-

这利用了简化问题的 CursorAdapter。但是，它确实需要一个专门命名为_id的列。但是，在此示例中，即使该列在表中不存在，它也是由用于获取所有客户 ( getAllCustomers) 的查询生成的。

选择时生成的 Spinner 看起来像使用库存布局simple_list_item_2：-

• 请注意，使用其他布局相对简单。

CursorAdapters （示例使用非常灵活的 SimpleCursorAdapter）的优点是它们被设计为与 Cursors 一起使用。诸如onSelectedItem之类的事件允许直接访问相应定位的源游标，并将_id的值传递给此类事件（参见示例中的代码onSelectedItem，因为这说明了这一点）。

• 由于_id列应该是 rowid 列的别名，因此它将始终唯一标识所选行（再次在 中演示onSelectedItem）。

该示例包括这样一个侦听器，它既可以发送消息，也可以将消息写入日志，例如（依次选择所有三个）：-

2019-12-04 07:50:30.008 7679-7679/? D/SELECTEDITEMINFO: You selected Customer >Mary CustomerID > 12345678
        The position in the List was 0
        The id passed to onItemSelected was 12345678
2019-12-04 07:50:33.828 7679-7679/a.so59159856spinner D/SELECTEDITEMINFO: You selected Customer >Agnes CustomerID > 22222222
        The position in the List was 1
        The id passed to onItemSelected was 22222222
2019-12-04 07:50:38.666 7679-7679/a.so59159856spinner D/SELECTEDITEMINFO: You selected Customer >Fred CustomerID > 84746464
        The position in the List was 2
        The id passed to onItemSelected was 84746464

• 请注意，当设置 Spinner 时，将触发 onSelectedItem。

这个例子

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Spinner
        android:id="@+id/myspinner"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
    </Spinner>

</LinearLayout>

数据库助手.java

public class DatabaseHelper extends SQLiteOpenHelper {

    public static final String DBNAME = "mydb";
    public static final int DBVERSION = 1;
    public static final String CUSTOMER_TABLE = "customer";
    public static final String CUSTOMER_COL_CUSTOMERID = "CustomerId";
    public static final String CUSTOMER_COL_CUSTOMER = "Customer";

    SQLiteDatabase mDB;

    public DatabaseHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
        mDB = this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(
                "CREATE TABLE IF NOT EXISTS " + CUSTOMER_TABLE +
                        "(" +
                        CUSTOMER_COL_CUSTOMERID + " INTEGER PRIMARY KEY," +
                        CUSTOMER_COL_CUSTOMER + " TEXT" +
                        ")"
        );
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
    public long insertCustomer(String customerId,String customer) {
        ContentValues cv = new ContentValues();
        cv.put(CUSTOMER_COL_CUSTOMER,customer);
        cv.put(CUSTOMER_COL_CUSTOMERID,customerId);
        return mDB.insert(CUSTOMER_TABLE,null,cv);
    }

    public Cursor getAllCustomers() {

        String[] columns = new String[]
                {
                CUSTOMER_COL_CUSTOMERID,
                CUSTOMER_COL_CUSTOMER,
                CUSTOMER_COL_CUSTOMERID + " AS " + BaseColumns._ID
        };
        return mDB.query(CUSTOMER_TABLE,columns,null,null,null,null,null);
    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {
    Spinner mSpinner;
    DatabaseHelper mDBHelper;
    Cursor mAllCustomers;
    SimpleCursorAdapter mSpinnerAdapter;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mSpinner = this.findViewById(R.id.myspinner);
        mDBHelper = new DatabaseHelper(this);
        addSomeTestingCustomers();
        manageSpinner();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        mAllCustomers.close(); /* Close the Cursor when done with it */
    }

    @Override
    protected void onResume() {
        super.onResume();
        manageSpinner(); /* Refresh the Spinner in case data has changed */
    }

    /* Manage the Spinner */
    private void manageSpinner() {
        mAllCustomers = mDBHelper.getAllCustomers();
        if (mSpinnerAdapter == null) {
            String[] columns_to_display = new String[]{
              DatabaseHelper.CUSTOMER_COL_CUSTOMERID,
              DatabaseHelper.CUSTOMER_COL_CUSTOMER
            };
            int[] views_in_which_data_is_displayed = new int[]{
                    android.R.id.text1,
                    android.R.id.text2
            };
            mSpinnerAdapter = new SimpleCursorAdapter(
                    this,
                    android.R.layout.simple_list_item_2,
                    mAllCustomers,
                    columns_to_display,
                    views_in_which_data_is_displayed,
                    0);
            mSpinner.setAdapter(mSpinnerAdapter);
            mSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                    String selected_info =
                            "You selected Customer >" +
                                    mAllCustomers.getString(mAllCustomers.getColumnIndex(DatabaseHelper.CUSTOMER_COL_CUSTOMER)) +
                                    " CustomerID > " +
                                    mAllCustomers.getString(mAllCustomers.getColumnIndex(DatabaseHelper.CUSTOMER_COL_CUSTOMERID)) +
                                    "\n\tThe position in the List was " + position +
                                    "\n\tThe id passed to onItemSelected was " + id
                            ;
                    Log.d("SELECTEDITEMINFO",selected_info);
                    Toast.makeText(
                            view.getContext(),
                            selected_info,
                            Toast.LENGTH_SHORT
                    ).show();
                }

                @Override
                public void onNothingSelected(AdapterView<?> parent) {

                }
            });
        } else {
            /* If the Spinner has been setup then refresh the List */
            /* This would be called whenever the Database has been (or might have been) changed */
            /* typically you would override the activities onResume method to call this */
            mSpinnerAdapter.swapCursor(mAllCustomers);
        }
    }

    /* Add some testing data to the database if none already exists */
    private void addSomeTestingCustomers() {
        if (DatabaseUtils.queryNumEntries(mDBHelper.getWritableDatabase(),DatabaseHelper.CUSTOMER_TABLE) < 1) {
            mDBHelper.insertCustomer("84746464","Fred");
            mDBHelper.insertCustomer("12345678","Mary");
            mDBHelper.insertCustomer("22222222","Agnes");
        }
    }
}