ListViewはすべてのボタンクリックで同じJSONアイテムを繰り返す

Question

私は主なアクティビティのListViewとJSONを取得するボタンを持っています。
ボタンクリックを繰り返すと、同じJSON要素がListViewに追加されます。

ボタンを再度クリックすると、リストビューをクリアするにはどうすればよいですか？

CustomListAdapterあなたは何度も何度も自分のvehicleListにJson objectの内容を追加している

public class SearchActivity extends Activity implements View.OnClickListener { 

    // Log tag 
    private static final String TAG = SearchActivity.class.getSimpleName(); 

    // Vehicles json url 
    private static final String url = "https://api.myjson.com/bins/3u7ty"; 
    private SweetAlertDialog pDialog; 
    private List<Vehicle> vehicleList = new ArrayList<Vehicle>(); 
    private ListView listView; 
    private CustomListAdapter adapter; 
    private Button buttonGet2; 


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


     buttonGet2 = (Button) findViewById(R.id.buttonGet2); 
     buttonGet2.setOnClickListener(this); 



    } 

    private void getData() { 
     listView=(ListView) findViewById(R.id.list2); 
     adapter=new CustomListAdapter(this,vehicleList); 
     listView.setAdapter(adapter); 
     final SweetAlertDialog pDialog = new SweetAlertDialog(this, SweetAlertDialog.PROGRESS_TYPE); 
     pDialog.getProgressHelper().setBarColor(Color.parseColor("#A5DC86")); 
     pDialog.setTitleText("Loading"); 
     pDialog.setCancelable(true); 

     // Showing progress dialog before making http request 
     pDialog.show(); 

     // changing action bar color 
     getActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#1b1b1b"))); 

     // Creating volley request obj 
     JsonArrayRequest vehicleReq = new JsonArrayRequest(url, 
       new Response.Listener<JSONArray>() { 
        @Override 
        public void onResponse(JSONArray response) { 
         Log.d(TAG, response.toString()); 
         pDialog.dismissWithAnimation(); 

         // Parsing json 
         for (int i = 0; i < response.length(); i++) { 
          try { 

           JSONObject obj = response.getJSONObject(i); 
           Vehicle vehicle = new Vehicle(); 
           vehicle.setTitle(obj.getString("title")); 
           vehicle.setThumbnailUrl(obj.getString("image")); 
           vehicle.setRating(((Number) obj.get("rating")) 
             .doubleValue()); 
           vehicle.setYear(obj.getInt("releaseYear")); 

           // Genre is json array 
           JSONArray genreArry = obj.getJSONArray("genre"); 
           ArrayList<String> genre = new ArrayList<String>(); 
           for (int j = 0; j < genreArry.length(); j++) { 
            genre.add((String) genreArry.get(j)); 
           } 
           vehicle.setGenre(genre); 

           // adding vehicle to vehicles array 
           vehicleList.add(vehicle); 

          } catch (JSONException e) { 
           e.printStackTrace(); 
          } 

         } 

         // notifying list adapter about data changes 
         // so that it renders the list view with updated data 
         adapter.notifyDataSetChanged(); 
        } 
       }, new Response.ErrorListener() { 
      @Override 
      public void onErrorResponse(VolleyError error) { 
       VolleyLog.d(TAG, "Error: " + error.getMessage()); 
       pDialog.dismissWithAnimation(); 

      } 
     }); 

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

    } 

    @Override 
    public void onClick(View v) { 
     getData(); 
    } 
} 

Answer 1

public class CustomListAdapter extends BaseAdapter { 
    private Activity activity; 
    private LayoutInflater inflater; 
    private List<Vehicle> vehicleItems; 
    ImageLoader imageLoader = AppController.getInstance().getImageLoader(); 

    public CustomListAdapter(Activity activity, List<Vehicle> vehicleItems) { 
     this.activity = activity; 
     this.vehicleItems = vehicleItems; 
    } 

    @Override 
    public int getCount() { 
     return vehicleItems.size(); 
    } 

    @Override 
    public Object getItem(int location) { 
     return vehicleItems.get(location); 
    } 

    @Override 
    public long getItemId(int position) { 
     return position; 
    } 

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

     if (inflater == null) 
      inflater = (LayoutInflater) activity 
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     if (convertView == null) 
      convertView = inflater.inflate(R.layout.list_row, null); 

     if (imageLoader == null) 
      imageLoader = AppController.getInstance().getImageLoader(); 
     NetworkImageView thumbNail = (NetworkImageView) convertView 
       .findViewById(R.id.thumbnail); 
     TextView title = (TextView) convertView.findViewById(R.id.title); 
     TextView rating = (TextView) convertView.findViewById(R.id.rating); 
     TextView genre = (TextView) convertView.findViewById(R.id.genre); 
     TextView year = (TextView) convertView.findViewById(R.id.releaseYear); 

     // getting movie data for the row 
     Vehicle m = vehicleItems.get(position); 

     // thumbnail image 
     thumbNail.setImageUrl(m.getThumbnailUrl(), imageLoader); 

     // title 
     title.setText(m.getTitle()); 

     // rating 
     rating.setText("Rating: " + String.valueOf(m.getRating())); 

     // genre 
     String genreStr = ""; 
     for (String str : m.getGenre()) { 
      genreStr += str + ", "; 
     } 
     genreStr = genreStr.length() > 0 ? genreStr.substring(0, 
       genreStr.length() - 2) : genreStr; 
     genre.setText(genreStr); 

     // release year 
     year.setText(String.valueOf(m.getYear())); 

     return convertView; 
    } 
} 

SearchActivity。 vehicleListにはまだ古い値が保持されています。その後、Jsonオブジェクトから再度値をキャッチし、それを再びvehicleListに追加します。これを取り除くために、リストをクリア：データをクリアするとともに

private void getData() { 
    vehicleList.clear(); 
    listView=(ListView) findViewById(R.id.list2); 
    adapter=new CustomListAdapter(this,vehicleList); 

//rest of your code 
} 

Answer 2

を、単にアダプタとリストの初期化を繰り返し、データを取得していないため、そのメソッドが唯一の責任を作ります。

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

    buttonGet2 = (Button) findViewById(R.id.buttonGet2); 
    buttonGet2.setOnClickListener(this); 

    // Moved these lines 
    listView = (ListView) findViewById(R.id.list2); 
    adapter = new CustomListAdapter(this,vehicleList); 
    listView.setAdapter(adapter); 


} 


private void getData() { 

    vehicleList.clear(); // Added this 

    final SweetAlertDialog pDialog = new SweetAlertDialog(this, SweetAlertDialog.PROGRESS_TYPE); 
    pDialog.getProgressHelper().setBarColor(Color.parseColor("#A5DC86")); 
    pDialog.setTitleText("Loading"); 
    pDialog.setCancelable(true);