Question

这给了我一个我可以使用的字符串值：

                    Cursor vTypeChose = (Cursor)(vTypeSpinner.getSelectedItem());
                    if (vTypeChose != null) {
                        typePicked = vTypeChose.getString(
                        vTypeChose.getColumnIndex(DataBaseHelper.POWERSPORTS_TYPE));
                    }

这给了我null：

vTypeSpinner.setOnItemSelectedListener(new OnItemSelectedListener(){

            public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int
                pos, long id) {
                 if(pos!=0){

                    Cursor vTypeChose = (Cursor)(vTypeSpinner.getSelectedItem());
                    if (vTypeChose != null) {
                        typePicked = vTypeChose.getString(
                        vTypeChose.getColumnIndex(DataBaseHelper.POWERSPORTS_TYPE));


                    }
                 }
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                // TODO Auto-generated method stub

            }
        });

在OnItemSelectedListener中使用Log.e和Toast以及typePicked变量向我显示它正在触发，只是没有传递给我正确的值。

如果没有OnItemSelectedListener，它会使用相关数据填充第二个微调器。添加OnItemSelectedListener后，第二个微调器将填充任何内容，因为字符串值为null。

（编辑）添加了代码：

public class PowersportsEquivalent extends Activity {

DataBaseHelper myDbHelper;
String typePicked = null;
String makePicked = null;

@SuppressWarnings("deprecation")
@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_powersports_equivalent);
    myDbHelper = new DataBaseHelper(this);
    try {
        myDbHelper.createDataBase();
    } catch (IOException ioe) {
        // TODO Auto-generated catch block
        throw new Error("Unable to create database");
    }

    try { 
        myDbHelper.openDataBase();
    }catch(SQLException sqle){
        throw sqle;

    }

    final Cursor vType;
    final Cursor vMake;
    final Spinner vTypeSpinner;
    final Spinner vMakeSpinner;


    //POWERSPORTS TYPE Cursor
    vType = (Cursor) DataBaseHelper.getPowersportsType();
    startManagingCursor(vType);

        SimpleCursorAdapter scaType = new SimpleCursorAdapter(this, 
                android.R.layout.simple_spinner_item, 
                vType,
                new String [] {DataBaseHelper.POWERSPORTS_TYPE},
                new int[] {android.R.id.text1});

        scaType.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        vTypeSpinner = (Spinner) findViewById(R.id.typeSpinner);
        vTypeSpinner.setAdapter(scaType);

    //POWERSPORTS MAKE Cursor

        vTypeSpinner.setOnItemSelectedListener(new OnItemSelectedListener(){

            public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int
                pos, long id) {
                 if(pos!=0){

                    Cursor vTypeChose = (Cursor)(vTypeSpinner.getSelectedItem());
                    if (vTypeChose != null) {
                        typePicked = vTypeChose.getString(
                        vTypeChose.getColumnIndex(DataBaseHelper.POWERSPORTS_TYPE));


                    }
                 }
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                // TODO Auto-generated method stub

            }
        });
    vMake = (Cursor) DataBaseHelper.getPowersportsMake(typePicked);
    startManagingCursor(vMake);

        SimpleCursorAdapter scaMake = new SimpleCursorAdapter(this, 
                android.R.layout.simple_spinner_item, 
                vMake,
                new String [] {DataBaseHelper.POWERSPORTS_MAKE},
                new int[]{android.R.id.text1});

        scaMake.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        vMakeSpinner = (Spinner) findViewById(R.id.makeSpinner);
        vMakeSpinner.setAdapter(scaMake);

Answer 1

也许尝试在pos参数中使用onItemSelected，然后通过适配器获取项目，如下所示：

public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int
                pos, long id) {
             if(pos!=0){

                Cursor vTypeChose = (Cursor) scaType.getItem(pos);
                if (vTypeChose != null) {
                    typePicked = vTypeChose.getString(
                    vTypeChose.getColumnIndex(DataBaseHelper.POWERSPORTS_TYPE));
                }
             }
        }

Answer 2

为了使用spin1选择相应地更新spin2，你必须在onItemSelected重新加载spin2数据。试试这个：

vTypeSpinner.setOnItemSelectedListener(new OnItemSelectedListener(){

    public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int
                pos, long id) {

        TextView picked = (TextView)selectedItemView;
        if(picked != null){

            typePicked = picked.getText().toString();
            vMake = (Cursor) DataBaseHelper.getPowersportsMake(typePicked);
            scaMake.changeCursor(vMake);
        }
   }
}

也改变。（此代码在onItemSelected之前运行，这就是为什么typePicked为空）

vMake = (Cursor) DataBaseHelper.getPowersportsMake(typePicked);
startManagingCursor(vMake);

    SimpleCursorAdapter scaMake = new SimpleCursorAdapter(this, 
            android.R.layout.simple_spinner_item, 
            vMake,
            new String [] {DataBaseHelper.POWERSPORTS_MAKE},
            new int[]{android.R.id.text1});

到

//vMake = (Cursor) DataBaseHelper.getPowersportsMake(typePicked);
//startManagingCursor(vMake);

    SimpleCursorAdapter scaMake = new SimpleCursorAdapter(this, 
            android.R.layout.simple_spinner_item, 
            null,
            new String [] {DataBaseHelper.POWERSPORTS_MAKE},
            new int[]{android.R.id.text1});

我认为在完成这些更改后，您可以使用原始代码。

另一种可能的方法是使用传递给此方法的id并直接从数据库

获取值

Answer 3

您的代码已编辑：

public class PowersportsEquivalent extends Activity {

    DataBaseHelper myDbHelper;
    String typePicked = null;
    String makePicked = null;
    final SimpleCursorAdapter scaMake;

    @SuppressWarnings("deprecation")
    @Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_powersports_equivalent);
        myDbHelper = new DataBaseHelper(this);
        try {
            myDbHelper.createDataBase();
        } catch (IOException ioe) {
            // TODO Auto-generated catch block
            throw new Error("Unable to create database");
        }

        try { 
            myDbHelper.openDataBase();
        }catch(SQLException sqle){
            throw sqle;

        }

        final Cursor vType;
        final Cursor vMake;
        final Spinner vTypeSpinner;
        final Spinner vMakeSpinner;


        //POWERSPORTS TYPE Cursor
        vType = (Cursor) DataBaseHelper.getPowersportsType();
        startManagingCursor(vType);

        SimpleCursorAdapter scaType = new SimpleCursorAdapter(this, 
                    android.R.layout.simple_spinner_item, 
                    vType,
                    new String [] {DataBaseHelper.POWERSPORTS_TYPE},
                    new int[] {android.R.id.text1});

        scaType.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        vTypeSpinner = (Spinner) findViewById(R.id.typeSpinner);
        vTypeSpinner.setAdapter(scaType);

        //POWERSPORTS MAKE Cursor

        vTypeSpinner.setOnItemSelectedListener(new OnItemSelectedListener(){

            public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int pos, long id) {

                if(pos!=0){

                    TextView picked = (TextView)selectedItemView;
                    if(picked != null){

                        typePicked = picked.getText().toString();
                        vMake = (Cursor) DataBaseHelper.getPowersportsMake(typePicked);
                        scaMake.changeCursor(vMake);    

                    }
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                    // TODO Auto-generated method stub

            }
        });

        //vMake = (Cursor) DataBaseHelper.getPowersportsMake(typePicked);
        //startManagingCursor(vMake);

        scaMake = new SimpleCursorAdapter(this, 
                    android.R.layout.simple_spinner_item, 
                    null,
                    new String [] {DataBaseHelper.POWERSPORTS_MAKE},
                    new int[]{android.R.id.text1});

        scaMake.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        vMakeSpinner = (Spinner) findViewById(R.id.makeSpinner);
        vMakeSpinner.setAdapter(scaMake);

空字符串值OnItemSelected

3 个答案: