没有默认的API来设置微调提示。为了添加它，我们需要一个小的解决方案，而不是安全反射实现

List<Object> objects = new ArrayList<Object>();
objects.add(firstItem);
objects.add(secondItem);
// add hint as last item
objects.add(hint);

HintAdapter adapter = new HintAdapter(context, objects, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

Spinner spinnerFilmType = (Spinner) findViewById(R.id.spinner);
spinner.setAdapter(adapter);

// show hint
spinner.setSelection(adapter.getCount());

适配器来源:

public class HintAdapter
        extends ArrayAdapter<Objects> {

    public HintAdapter(Context theContext, List<Object> objects) {
        super(theContext, android.R.id.text1, android.R.id.text1, objects);
    }

    public HintAdapter(Context theContext, List<Object> objects, int theLayoutResId) {
        super(theContext, theLayoutResId, android.R.id.text1, objects);
    }

    @Override
    public int getCount() {
        // don't display last item. It is used as hint.
        int count = super.getCount();
        return count > 0 ? count - 1 : count;
    }
}

原始来源

When extending SpinnerAdapter, you override two View-producing methods, getView(int, View, ViewGroup) and getDropDownView(int, View, ViewGroup). The first one supplies the View inserted into the Spinner itself; the second supplies the View in the drop-down list (as the name suggests). You can override the getView(...) so that, until an item has been selected, it displays a TextView containing a prompt; then, when you detect an item has been selected, you change it to display a TextView corresponding to that.

public class PromptingAdapter extends SpinnerAdapter {

    //... various code ...

    private boolean selectionmade = false;

    //call this method from the OnItemSelectedListener for your Spinner
    public setSelectionState(boolean b) {
        selectionmade = b;
    }

    @Override
    public View getView(int position, View recycle, ViewGroup container) {
        if(selectionmade) {
            //your existing code to supply a View for the Spinner
            //you could even put "return getDropDownView(position, recycle, container);"
        }
        else {
            View output;
            if(recycle instanceof TextView) {
                 output = recycle;
            }
            else {
                 output = new TextView();
                 //and layout stuff
            }
            output.setText(R.string.please_select_one);
            //put a string "please_select_one" in res/values/strings.xml
            return output;
        }
    }

//...
}

此代码已经过测试，在Android 4.4上工作

Spinner spinner = (Spinner) activity.findViewById(R.id.spinner);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(activity, android.R.layout.simple_spinner_dropdown_item) {

            @Override
            public View getView(int position, View convertView, ViewGroup parent) {

                View v = super.getView(position, convertView, parent);
                if (position == getCount()) {
                    ((TextView)v.findViewById(android.R.id.text1)).setText("");
                    ((TextView)v.findViewById(android.R.id.text1)).setHint(getItem(getCount())); //"Hint to be displayed"
                }

                return v;
            }       

            @Override
            public int getCount() {
                return super.getCount()-1; // you dont display last item. It is used as hint.
            }

        };

        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        adapter.add("Daily");
        adapter.add("Two Days");
        adapter.add("Weekly");
        adapter.add("Monthly");
        adapter.add("Three Months");
        adapter.add("HINT_TEXT_HERE"); //This is the text that will be displayed as hint.


        spinner.setAdapter(adapter);
        spinner.setSelection(adapter.getCount()); //set the hint the default selection so it appears on launch.
        spinner.setOnItemSelectedListener(this);

如果您在从数据库游标填充项时遇到此问题，

我在这个SO答案中找到的最简单的解决方案:

在游标适配器查询中使用UNION，并将id= -1的附加项添加到查询结果中，而不真正将其添加到DB中:

喜欢的东西:

db.rawQuery("SELECT iWorkerId as _id, nvLastName as name  FROM  Worker
w  UNION  SELECT -1 as _id , '' as name",null);

如果选择的项目是-1，那么它是默认值。否则 这是桌子上的记录。

这里有很多答案，但我很惊讶没有人提出一个简单的解决方案:在旋转器的顶部放置一个TextView。在TextView上设置一个点击监听器，它隐藏了显示Spinner的TextView，并调用spiner . performclick()。

没有默认的API来设置微调提示。为了添加它，我们需要一个小的解决方案，而不是安全反射实现

List<Object> objects = new ArrayList<Object>();
objects.add(firstItem);
objects.add(secondItem);
// add hint as last item
objects.add(hint);

HintAdapter adapter = new HintAdapter(context, objects, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

Spinner spinnerFilmType = (Spinner) findViewById(R.id.spinner);
spinner.setAdapter(adapter);

// show hint
spinner.setSelection(adapter.getCount());

适配器来源:

public class HintAdapter
        extends ArrayAdapter<Objects> {

    public HintAdapter(Context theContext, List<Object> objects) {
        super(theContext, android.R.id.text1, android.R.id.text1, objects);
    }

    public HintAdapter(Context theContext, List<Object> objects, int theLayoutResId) {
        super(theContext, theLayoutResId, android.R.id.text1, objects);
    }

    @Override
    public int getCount() {
        // don't display last item. It is used as hint.
        int count = super.getCount();
        return count > 0 ? count - 1 : count;
    }
}

原始来源