Question

我使用带游标适配器的下拉微调器。它包含例如1到100个项目。我选择例如项目50.项目已被选中。下次当我打开微调器时，第一个可见行是第50项。当我打开微调器时，我将如何实现它将聚焦到第一个项目/第一个可见项目将是第1项？

我的意思是在列表中自动滚动，因此下拉列表中的第一个可见项目是第一个，而不是一个。

Answer 1

您可以通过扩展Spinner来执行您想要的操作，并覆盖负责设置/显示值列表的两种方法：

public class CustomSpinnerSelection extends Spinner {

    private boolean mToggleFlag = true;

    public CustomSpinnerSelection(Context context, AttributeSet attrs,
            int defStyle, int mode) {
        super(context, attrs, defStyle, mode);
    }

    public CustomSpinnerSelection(Context context, AttributeSet attrs,
            int defStyle) {
        super(context, attrs, defStyle);
    }

    public CustomSpinnerSelection(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomSpinnerSelection(Context context, int mode) {
        super(context, mode);
    }

    public CustomSpinnerSelection(Context context) {
        super(context);
    }

    @Override
    public int getSelectedItemPosition() {
        // this toggle is required because this method will get called in other
        // places too, the most important being called for the
        // OnItemSelectedListener
        if (!mToggleFlag) {
            return 0; // get us to the first element
        }
        return super.getSelectedItemPosition();
    }

    @Override
    public boolean performClick() {
        // this method shows the list of elements from which to select one.
        // we have to make the getSelectedItemPosition to return 0 so you can
        // fool the Spinner and let it think that the selected item is the first
        // element
        mToggleFlag = false;
        boolean result = super.performClick();
        mToggleFlag = true;
        return result;
    }

}

它应该适合您想要做的事情。

Answer 2

您可以将Spinner的选择设置为第一项，如下所示：

yourspinner.setSelection(0);

您可能希望在onStart（）方法中执行此操作。

Answer 3

这段代码将为您完成工作。

    int prevSelection=0;
    spSunFrom = (Spinner) findViewById(R.id.spTimeFromSun);
    spSunFrom.setOnTouchListener(new OnTouchListener() {

        public boolean onTouch(View v, MotionEvent event) {
            // TODO Auto-generated method stub
            prevSelection = spSunFrom.getSelectedItemPosition();
            spSunFrom.setSelection(0);
            return false;
        }
    });
    spSunFrom.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int arg2, long arg3) {
            if(arg2==0)
                spSunFrom.setSelection(prevSelection);
            prevSelection = arg2;

        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {
            spSunFrom.setSelection(prevSelection);
        }
    });

微调器 - 专注于第一项

3 个答案: