单击列表时重复的微调器数据

Question

在活动 B 中有一个 spinner，其中的数据来自 MySQL（表格位置）。

活动 B

private ArrayList<String> froms;
private JSONArray resultFrom;

public void addItemsOnFrom() {

    travelFrom = (Spinner) findViewById(R.id.travelFrom);
    StringRequest stringRequest = new StringRequest(Configs.FROM_URL,
            new Response.Listener<String>() {

                @Override
                public void onResponse(String response) {
                    JSONObject j = null;
                    try {
                        //Parsing the fetched Json String to JSON Object
                        j = new JSONObject(response);

                        //Storing the Array of JSON String to our JSON Array
                        resultFrom = j.getJSONArray(Configs.JSON_ARRAY);

                        //Calling method getStudents to get the students from the JSON Array
                        getFrom(resultFrom);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //Creating a request queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //Adding request to the queue
    requestQueue.add(stringRequest);
}

private void getFrom(JSONArray j) {
    //Traversing through all the items in the json array
    for (int i = 0; i < j.length(); i++) {
        try {
            //Getting json object
            JSONObject json = j.getJSONObject(i);

            //Adding the name of the student to array list
            froms.add(json.getString(Configs.TAG_LOCATION));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    //Setting adapter to show the items in the spinner
    travelFrom.setAdapter(new ArrayAdapter<String>(Add_Details_Information.this, android.R.layout.simple_spinner_dropdown_item, froms));
}

当点击保存button时，它会将选择的值（OFFICE）返回给活动AlistView。而在Activity A中，当列表被按下时，它会intent到Activity B。此时，Activity B中的spinner将首先显示被选中的项目（OFFICE）。

**Table location**  // table location has 2 data
NONE 
OFFICE

假设B中选择了OFFICE，点击列表时，我希望OFFICE首先显示在spinnerB中。

活动 B 中的代码，用于首先显示 OFFICE。

if(getIntent().getExtras()!=null)
{ 
    final String from = getIntent().getStringExtra("from");
    selectedItemFrom(from);
}

---

public void selectedItemFrom(final String value)// display  OFFICE first
{
    travelFrom = (Spinner) findViewById(R.id.travelFrom);
    StringRequest stringRequest = new StringRequest(Configs.FROM_URL,
            new Response.Listener<String>() {

                @Override
                public void onResponse(String response) {
                    JSONObject j = null;
                    try {
                        //Parsing the fetched Json String to JSON Object
                        j = new JSONObject(response);

                        //Storing the Array of JSON String to our JSON Array
                        result = j.getJSONArray(Configs.JSON_ARRAY);

                        //Calling method getStudents to get the students from the JSON Array
                        getFrom(result, value);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //Creating a request queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //Adding request to the queue
    requestQueue.add(stringRequest);
}

private void getFrom(JSONArray j, String value) {
    int position = 0;
    //Traversing through all the items in the json array
    for (int i = 0; i < j.length(); i++) {
        try {
            //Getting json object
            JSONObject json = j.getJSONObject(i);
            //Adding the name of the student to array list
            froms.add(json.getString(Configs.TAG_LOCATION));
            if (froms.get(i).equalsIgnoreCase(value)) {

                position = i;
                //Toast.makeText(getApplicationContext(),position+"",Toast.LENGTH_LONG).show();
                break;
            }


        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
    travelFrom.setAdapter(new ArrayAdapter<String>(Add_Details_Information.this, android.R.layout.simple_spinner_dropdown_item, froms));
    travelFrom.setSelection(position);
}

OFFICE 可以先显示，但问题是当我检查微调器 B 时，它显示 NONE,OFFICE,NONE OFFICE ..为什么微调器数据会重复？谢谢

我认为问题出在这一行travelFrom.setAdapter(new ArrayAdapter<String>(Add_Details_Information.this, android.R.layout.simple_spinner_dropdown_item, froms));...但是如何解决？？？有人吗？

有时微调器会先显示所选项目，但有时不会...有什么更好的书写方式？

编辑

{"result":[{"name":"NONE"},{"name":"OFFICE"}]}

我现在将 forms.clear 放在两个 getFrom 方法的开头。但问题是当我选择 NONE 并返回 A，然后再次转到 B 时，微调器现在只有 NONE...

Answer 1

请尝试这样的事情。

此活动将需要一个带有键 "from" 的 Intent，该键设置为 "NONE" 或 "OFFICE"。如果意图没有数据，那么它将默认为首先插入到 Spinner 中的任何内容。

public class MainActivity extends AppCompatActivity {

    private Spinner travelFrom;
    private ArrayAdapter<String> mSpinnerAdapter;
    private List<String> mSpinnerData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        String from = null;
        Bundle extras = getIntent().getExtras();
        if (extras != null) {
            from = extras.getString("from");
        }

        setupFromSpinner(from);
    }

    private void setupFromSpinner(final String value) {
        travelFrom = (Spinner) findViewById(R.id.travelFrom);
        mSpinnerData = new ArrayList<String>();
        mSpinnerAdapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_spinner_item, mSpinnerData);
        mSpinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        travelFrom.setAdapter(mSpinnerAdapter);

        JsonObjectRequest req = new JsonObjectRequest(Configs.FROM_URL,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {
                        mSpinnerData.clear();
                        try {
                            JSONArray resultFrom = response.getJSONArray("result");
                            for (int i = 0; i < resultFrom.length(); i++) {
                                JSONObject fromObj = resultFrom.getJSONObject(i);
                                String name = fromObj.getString("name");
                                mSpinnerData.add(name);
                            }
                            mSpinnerAdapter.notifyDataSetChanged();
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }

                        if (value != null) {
                            int position = mSpinnerAdapter.getPosition(value);
                            travelFrom.setSelection(position);
                        } else {
                            travelFrom.setSelection(0);
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                }
        );

        //Creating a request queue
        RequestQueue requestQueue = Volley.newRequestQueue(this);

        //Adding request to the queue
        requestQueue.add(req);
    }
}

Answer 2

将 froms.clear() 添加到这段代码中；

private void getFrom(JSONArray j) {
    //Traversing through all the items in the json array
    froms.clear();
    for (int i = 0; i < j.length(); i++) {
        try {
            //Getting json object
            JSONObject json = j.getJSONObject(i);

            //Adding the name of the student to array list
            froms.add(json.getString(Configs.TAG_LOCATION));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    //Setting adapter to show the items in the spinner
    travelFrom.setAdapter(new ArrayAdapter<String>(Add_Details_Information.this, android.R.layout.simple_spinner_dropdown_item, froms));
}