Question

这里使用来自json url的动态值填充微调器。我在微调器中获得了值，但是当选择如下所示时它们是不可见的。

    @Override

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.spintoolbaractivity);
    toolbar = (Toolbar) findViewById(R.id.toolbar);
    spinner_nav = (Spinner) findViewById(R.id.spinner_nav);
    if (toolbar != null) {
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayShowTitleEnabled(false);

    }
    new GetTeacher().execute();

}
private class GetTeacher extends AsyncTask<Void, Void, Void>
{

    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(SpinToolbarActivity.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();

    }

    @Override
    protected Void doInBackground(Void... arg0)
    {
        Lclasslist = new ArrayList<String>();
        JsonObjectRequest req = new JsonObjectRequest(
                url_all_teacher, null, new    Response.Listener<JSONObject>(){
            @Override
            public void onResponse(JSONObject jsonObj) {
                Log.d("reponse", jsonObj.toString());

                try {
                    if (jsonObj != null)
                    {



                        class_details = jsonObj.getJSONArray(TAG_class_details);
                            String loginToken=class_details.toString();
                            String fstr=loginToken.substring(1, loginToken.length() - 1);
                            JSONObject jsonObj2 = new JSONObject(fstr);
                            JSONObject d = class_details.getJSONObject(0);

                            int success2 =d.getInt(TAG_SUCCESS);

                            if (success2 == 1)
                            {
                                class_details2= jsonObj2.getJSONArray(TAG_class_details2);
                                // looping through All Products
                                for (int i = 0; i < class_details2.length(); i++)
                                {
                                    JSONObject c = class_details2.getJSONObject(i);

// adding ArrayList and this list is added to spinner   
                            Lclasslist.add(c.getString("class_id"));

                                }
                            }
                            else
                            {
                                //setnoclssp();

                            }

                    } else {
                        //Log.e("ServiceHandler", "Couldn't get any data from the url");
                    }


                } catch (JSONException e) {
                    e.printStackTrace();
                    Toast.makeText(getApplicationContext(),
                            "Error: " + e.getMessage(),
                            Toast.LENGTH_LONG).show();
                }

                hidepDialog();
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                VolleyLog.d(TAG_class_details, "Error: " + error.getMessage());
                Toast.makeText(getApplicationContext(),
                        error.getMessage(), Toast.LENGTH_SHORT).show();
                hidepDialog();
            }
        });

        // Adding request to request queue
        AppController.getInstance().addToRequestQueue(req);

        return null;
    }
    @Override
    protected void onPostExecute (Void result)
    {
        addItemsToSpinner();
    }


}

//动态地将项目添加到微调器中

public void addItemsToSpinner()

{

//自定义ArrayAdapter，使用微调器项布局设置弹出背景

          CustomSpinnerAdapter spinAdapter = new CustomSpinnerAdapter(
         getApplicationContext(), Lclasslist);
         spinner_nav.setAdapter(spinAdapter);
         spinner_nav.setOnItemSelectedListener(new       OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> adapter, View v,
                int position, long id) {
            // On selecting a spinner item
            String item = adapter.getItemAtPosition(position).toString();

            // Showing selected spinner item
            Toast.makeText(getApplicationContext(), "Selected  : " + item,
                    Toast.LENGTH_LONG).show();
        }

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

        }
    });

}
private void showpDialog() {
    if (!pDialog.isShowing())
        pDialog.show();
}

private void hidepDialog() {
    if (pDialog.isShowing())
        pDialog.dismiss();
}

Image when i select spinner

Image when i select spinner item

Answer 1

更改方法addItemsToSpinner（）。

addItemsToSpinner（）：

public void addItemsToSpinner(){

 final ArrayAdapter<String> adapter= new ArrayAdapter<>
 (getApplicationContext(),android.R.layout.simple_spinner_item,Lclasslist);
  adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
  sp1.setAdapter(adapter);

}

在onCreate（）

中使用onItemSelected outide这个方法

sp1.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
            // TODO Auto-generated method stub


            String selectedItem = sp1.getSelectedItem().toString();
            Toast.makeText(getApplicationContext(), selectedItem, Toast.LENGTH_SHORT).show();

        }

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

        }
    });

这应该有效，一切顺利。

Answer 2

首先，你不应该在适配器中实现itemSelectedListenet，否则你应该在oncreate活动方法中实现它。尝试将其放入oncreate并检查它是否有效。此外，如果你只是想随时获得所选项目，那么点击你可能不需要onItemSelectedListenr而不是你可以使用

 yourSpinner.getSelectedItem();

希望这会有所帮助。

Spinner OnItemSelectedListener无法正常工作，并且微调器未在微调器

2 个答案: