我想使用一个微调器,最初(当用户还没有做出选择时)显示文本“Select One”。当用户单击微调器时,将显示项目列表,用户可以选择其中一个选项。用户做出选择后,所选项目将显示在微调器中,而不是“Select One”。

我有以下代码来创建一个旋转器:

String[] items = new String[] {"One", "Two", "Three"};
Spinner spinner = (Spinner) findViewById(R.id.mySpinner);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_item, items);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);

使用这段代码,最初会显示项目“One”。我可以在项目中添加一个新项目“Select One”,但“Select One”也会作为第一项显示在下拉列表中,这不是我想要的。

我该如何解决这个问题?


当前回答

private boolean isFirst = true;
private void setAdapter() {
    final ArrayList<String> spinnerArray = new ArrayList<String>();     
    spinnerArray.add("Select your option");
    spinnerArray.add("Option 1");
    spinnerArray.add("Option 2");
    spin.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
            TextView tv = (TextView)selectedItemView;
            String res = tv.getText().toString().trim();
            if (res.equals("Option 1")) {
            //do Something
        } else if (res.equals("Option 2")) {
            //do Something else
        }
        }

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

    });
            
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.my_spinner_style,spinnerArray) {
         public View getView(int position, View convertView, ViewGroup parent) {
             View v = super.getView(position, convertView, parent);
             int height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 25, getResources().getDisplayMetrics());                  
             ((TextView) v).setTypeface(tf2);
             ((TextView) v).getLayoutParams().height = height;
             ((TextView) v).setGravity(Gravity.CENTER);
             ((TextView) v).setTextSize(TypedValue.COMPLEX_UNIT_SP, 19);
             ((TextView) v).setTextColor(Color.WHITE);
             return v;
         }

         public View getDropDownView(int position, View convertView,
                 ViewGroup parent) {
             if (isFirst) {
                 isFirst = false;
                 spinnerArray.remove(0);
             }
             View v = super.getDropDownView(position, convertView, parent);                  
             ((TextView) v).setTextColor(Color.argb(255, 70, 70, 70));
             ((TextView) v).setTypeface(tf2);
             ((TextView) v).setGravity(Gravity.CENTER);
             return v;
         }
     };
     spin.setAdapter(adapter);
}

其他回答

你可以把它变成一个文本视图,并使用这个:

android:style="@android:style/Widget.DeviceDefault.Light.Spinner"

然后定义android:text属性。

对我来说,它是这样工作的。有改进,只改变文本在某些选项,而不是全部。

首先,我采用旋转器的名称并创建带有自定义视图的arrayadapter,但现在这并不重要,关键是覆盖getView,并在内部更改你需要更改的值。在我的情况下只有第一个,其余的我离开原来的

public void rellenarSpinnerCompeticiones(){
        spinnerArrayCompeticiones = new ArrayList<String>();
        for(Competicion c: ((Controlador)getApplication()).getCompeticiones()){
            spinnerArrayCompeticiones.add(c.getNombre());
        }
        //ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this,R.layout.spinner_item_competicion,spinnerArrayCompeticiones);
        ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, R.layout.spinner_item_competicion, spinnerArrayCompeticiones){
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                final View v = vi.inflate(R.layout.spinner_item_competicion, null);
                final TextView t = (TextView)v.findViewById(R.id.tvCompeticion);
                if(spinnerCompeticion.getSelectedItemPosition()>0){
                    t.setText(spinnerArrayCompeticiones.get(spinnerCompeticion.getSelectedItemPosition()));
                }else{
                    t.setText("Competiciones");
                }
                return v;
            }
        };
        spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinnerCompeticion.setAdapter(spinnerArrayAdapter);
    }

看到答案与轻量级和高可定制的库:

https://stackoverflow.com/a/73085435/6694920

<com.innowisegroup.hintedspinner.HintedSpinner
android:id="@+id/hintedSpinner"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginHorizontal="20dp"
app:hintTextSize="24sp"
app:hintTextColor="@color/red"
app:hint="Custom hint"
app:withDivider="true"
app:dividerColor="@color/dark_green"
app:arrowDrawable="@drawable/example_arrow_4"
app:arrowTint="@color/colorAccent"
app:popupBackground="@color/light_blue"
app:items="@array/text" />

倒塌的微调器:

扩大转轮:

public AdapterView.OnItemSelectedListener instructorSpinnerListener = new AdapterView.OnItemSelectedListener() {
    @Override
    public void onItemSelected(AdapterView << ? > adapterView, View view, int i, long l) {
        String selectedInstructorName = adapterView.getItemAtPosition(i).toString();
        if (selectedInstructorName.equals("[Select Instructor]")) {
            instructorSpinnerAdapter.clear();
            for (Offering offering: allOfferingsList)
                instructorSpinnerAdapter.add(offering);
        } else {
            instructorSpinnerAdapter.clear();
        }
    }

    @Override
    public void onNothingSelected(AdapterView<< ? > adapterView) {
        adapterView.setSelection(0);

        // Toast.makeText(getApplicationContext(), "Why?", Toast.LENGTH_SHORT).show();
    }
};

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;
        }
    }

//...
}