android - 如何使用 mysql 数据库中的数据填充 Android spinner

Question

我正在尝试从 mysql 数据库检索一些数据，以便用该数据填充微调器。我设法将 spinner 中的数据插入到 mysql 数据库中，但是当我尝试检索时，Logcat 中显示 spinner 为空! 我在网上搜索，但找不到解决我的问题的方法。

这里是从 mysql 数据库检索数据的 java 代码:

private static final String TAG_FACULTY_NAME = "faculty_name";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.editactivity); //Connected to XML file for the interface

    // save button
    btnSave = (Button) findViewById(R.id.lecturerSave);

    //Sharedpreference to get lecturer details
    SharedPreferences sp = getSharedPreferences("logindetails", 0);

    uid = sp.getString("uid", "-1");

    // Getting complete lecturer details in background thread
    new GetLecturerDetails().execute();


    // save button click event
    btnSave.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // starting background task to update lecturer account
                new SaveLecturerDetails().execute();

        }
    });

}

/**
 * Background Async Task to Get complete lecturer account details
 * */
class GetLecturerDetails extends AsyncTask<String, String, String> {

    /**
     * Before starting background thread Show Progress Dialog
     * */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(EditActivity.this);
        pDialog.setMessage("Loading. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show();
    }

    /**
     * Getting lecturer account details in background thread
     * */
    protected String doInBackground(String... params) {

         //updating UI from Background Thread
       // runOnUiThread(new Runnable() {
         //   public void run() {
                // Check for success tag
                int success;

                try {
                    // Building Parameters
                    List<NameValuePair> params1 = new ArrayList<NameValuePair>();
                    params1.add(new BasicNameValuePair("uid", uid));

                    // getting lecturer account details by making HTTP request
                    // Note that lecturer account details url will use GET request
                    JSONObject json = jsonParser.makeHttpRequest(
                            url_lecturer_details, "GET", params1);

                    // check your log for json response
                    Log.d("Single Product Details", json.toString());

                    // json success tag
                    success = json.getInt(TAG_SUCCESS);
                    if (success == 1) {
                        // successfully received lecturer account details
                        JSONArray productObj = json
                                .getJSONArray(TAG_PRODUCT); // JSON Array

                        // get first lecturer account object from JSON Array
                        final JSONObject product = productObj.getJSONObject(0);

                        // lecturer account with this uid found
                        // Edit Text
                        runOnUiThread(new Runnable() {
                               public void run() {

                        txtdrop_down = (Spinner) findViewById(R.id.spinner_faculty);


                        // display lecturer data in EditText


                        try
                        {

                        txtdrop_down.setTag(product.getString(TAG_FACULTY_NAME));
                        }catch (JSONException e)
                        {
                            e.printStackTrace();
                        }
                               }
                        });

                    } else{
                        // lecturer account with uid not found
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }


        return null;
            }



    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(String file_url) {
        // dismiss the dialog once got all details
        pDialog.dismiss();


    }
}

这是我从 Logcat 收到的错误:

11-23 12:25:02.543: E/AndroidRuntime(2499): FATAL EXCEPTION: main
11-23 12:25:02.543: E/AndroidRuntime(2499): java.lang.NullPointerException
11-23 12:25:02.543: E/AndroidRuntime(2499):     at android.widget.Spinner$DialogPopup.show(Spinner.java:935)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at android.widget.Spinner.performClick(Spinner.java:614)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at android.view.View$PerformClick.run(View.java:17721)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at android.os.Handler.handleCallback(Handler.java:730)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at android.os.Handler.dispatchMessage(Handler.java:92)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at android.os.Looper.loop(Looper.java:137)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at android.app.ActivityThread.main(ActivityThread.java:5103)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at java.lang.reflect.Method.invokeNative(Native Method)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at java.lang.reflect.Method.invoke(Method.java:525)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-23 12:25:02.543: E/AndroidRuntime(2499):     at dalvik.system.NativeStart.main(Native Method)

您能帮我解决这个问题吗？ 谢谢。

Answer 1

Android Hive Link

上面的链接有一个示例，该示例在运行时从用户处获取值并将其存储在数据库中，然后将其显示在 Spinner 中。它将向您展示如何从数据库获取值并在 Spinner 中显示它