索引超出界限時調用arraylist中的一個項目

我想獲取數組列表中的一個項目，但它給了我錯誤java.lang.IndexOutOfBoundsException：索引1無效，大小爲0 我把這個listEvent.get（1 ）.getTotal（）其中listEvent是我的arraylist 我如何從arraylist檢索一個元素？索引超出界限時調用arraylist中的一個項目

這裏是我的代碼

private void getData() { 
     //Adding the method to the queue by calling the method getDataFromServer 

     requestQueue.add(getDataFromServer(requestCount)); 
     //Incrementing the request counter 

     if(requestCount <= **listEvent.get(1).getTotal()**) { 
      requestCount++; 
     } 
    }

這裏是我的全部代碼

import android.content.Context; 
import android.content.Intent; 
import android.net.Uri; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v4.widget.SwipeRefreshLayout; 
import android.support.v7.widget.DefaultItemAnimator; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.view.GestureDetector; 
import android.view.LayoutInflater; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ProgressBar; 
import android.widget.Toast; 

import com.anakacara.anakacara.App.AppConfig; 
import com.anakacara.anakacara.App.Event; 
import com.anakacara.anakacara.Helper.CardAdapter; 
import com.anakacara.anakacara.R; 
import com.anakacara.anakacara.activity.DetailEvent; 
import com.android.volley.RequestQueue; 
import com.android.volley.Response; 
import com.android.volley.VolleyError; 
import com.android.volley.toolbox.JsonArrayRequest; 
import com.android.volley.toolbox.Volley; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.util.ArrayList; 
import java.util.List; 

/** 
* A simple {@link Fragment} subclass. 
* Activities that contain this fragment must implement the 
* {@link EventFragment.OnFragmentInteractionListener} interface 
* to handle interaction events. 
* Use the {@link EventFragment#newInstance} factory method to 
* create an instance of this fragment. 
*/ 
public class EventFragment extends Fragment implements SwipeRefreshLayout.OnRefreshListener { 
    // TODO: Rename parameter arguments, choose names that match 
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER 
    private static final String ARG_PARAM1 = "param1"; 
    private static final String ARG_PARAM2 = "param2"; 

    // TODO: Rename and change types of parameters 
    private String mParam1; 
    private String mParam2; 

    //Creating a List of event 
    private List<Event> listEvent; 

    //Creating Views 
    private RecyclerView recyclerView; 
    private RecyclerView.LayoutManager layoutManager; 
    private RecyclerView.Adapter adapter; 
    private int requestCount = 1; 
    private OnFragmentInteractionListener mListener; 
    private RequestQueue requestQueue; 
    private ProgressBar progressBar; 
    private SwipeRefreshLayout swipeRefreshLayout; 
    public EventFragment() { 
     // Required empty public constructor 
    } 

    /** 
    * Use this factory method to create a new instance of 
    * this fragment using the provided parameters. 
    * 
    * @param param1 Parameter 1. 
    * @param param2 Parameter 2. 
    * @return A new instance of fragment EventFragment. 
    */ 
    // TODO: Rename and change types and number of parameters 
    public static EventFragment newInstance(String param1, String param2) { 
     EventFragment fragment = new EventFragment(); 
     Bundle args = new Bundle(); 
     args.putString(ARG_PARAM1, param1); 
     args.putString(ARG_PARAM2, param2); 
     fragment.setArguments(args); 
     return fragment; 
    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     if (getArguments() != null) { 
      mParam1 = getArguments().getString(ARG_PARAM1); 
      mParam2 = getArguments().getString(ARG_PARAM2); 
     } 
    } 

    private final RecyclerView.OnScrollListener onScrollListener = new RecyclerView.OnScrollListener() { 
     @Override 
     public void onScrollStateChanged(final RecyclerView recyclerView, final int newState) { 
      // code 
      if (isLastItemDisplaying(recyclerView)) { 
       //Calling the method getdata again 
       getData(); 
      } 
     } 

     @Override 
     public void onScrolled(final RecyclerView recyclerView, final int dx, final int dy) { 
      // code 
      if (isLastItemDisplaying(recyclerView)) { 
       //Calling the method getdata again 
       getData(); 
      } 
     } 
    }; 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 
     View x = inflater.inflate(R.layout.fragment_event,null);; 
     progressBar = (ProgressBar) x.findViewById(R.id.progressBar1); 
     recyclerView = (RecyclerView) x.findViewById(R.id.recyclerView); 
     recyclerView.setHasFixedSize(true); 
     layoutManager = new LinearLayoutManager(getActivity()); 
     recyclerView.setLayoutManager(layoutManager); 
     swipeRefreshLayout = (SwipeRefreshLayout) x.findViewById(R.id.swipeRefreshLayout); 
     swipeRefreshLayout.setOnRefreshListener(this); 

     /** 
     * Showing Swipe Refresh animation on activity create 
     * As animation won't start on onCreate, post runnable is used 
     */ 
     swipeRefreshLayout.post(new Runnable() { 
            @Override 
            public void run() { 
             swipeRefreshLayout.setRefreshing(true); 

             getData(); 
            } 
           } 
     ); 




     //Initializing our event list 
     listEvent = new ArrayList<>(); 
     requestQueue = Volley.newRequestQueue(getActivity()); 
     //Calling method to get data 
     getData(); 

//  swipeRefreshLayout= (SwipeRefreshLayout) x.findViewById(R.id.swipeRefreshLayout); 
//  swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() 
//  { 
//   @Override 
//   public void onRefresh() 
//   { 
//    if (isLastItemDisplaying(recyclerView)) { 
////Calling the method getdata again 
//     getData(); 
//     progressBar.setVisibility(View.GONE); 
//    } 
//   } 
//  }); 
     recyclerView.addOnScrollListener(rVOnScrollListener); 
     adapter = new CardAdapter(listEvent, getActivity()); 

     //Adding adapter to recyclerview 
     recyclerView.setAdapter(adapter); 
     RecyclerView.ItemAnimator itemAnimator = new DefaultItemAnimator(); 
     itemAnimator.setAddDuration(1000); 
     itemAnimator.setRemoveDuration(1000); 
     recyclerView.setItemAnimator(itemAnimator); 
     recyclerView.addOnItemTouchListener(new RecyclerTouchListener(getActivity(), recyclerView, new ClickListener() { 
      @Override 
      public void onClick(View view, int position) { 
       Intent intent = new Intent(getActivity(), DetailEvent.class); 
       intent.putExtra("event_judul", listEvent.get(position).getJudul()); //you can name the keys whatever you like 
       intent.putExtra("event_deskripsi", listEvent.get(position).getDeskripsi()); //note that all these values have to be primitive

這裏是我的JSON代碼

0: { 
"id": 5 
"judul": "asdfasdfasdf" 
"deskripsi": "asfasdfasdfqwer" 
"duit": 123123 
"persen": 65 
"sisahari": 43 
"gambar": "http://192.168.0.13/task_manager/image/not4.jpeg" 
"total": 4 
}- 
1: { 
"id": 4 
"judul": "asdfasfasdfas" 
"deskripsi": "dafasdfasdfasdfasfdasdf" 
"duit": 12341234 
"persen": 12 
"sisahari": 31 
"gambar": "http://192.168.0.13/task_manager/image/not3.jpeg" 
"total": 4 
}

我需要訪問總，但是因爲在陣列0和1它是同樣我只需要訪問其中之一我想使用這樣的代碼 if（requestCount < = 4）{request_ount ++; } 這是4是頁面限制，但我想從數組中獲得它，所以它將是動態的，而不是像這樣的手動

來源

2016-03-13 Philipus Silaen

錯誤描述了您正在嘗試訪問空列的arraylist位置。
如果您要訪問的ArrayList位置1，你可以保持這樣的檢查試圖在那個現在的位置，這將確保您的應用程序不會崩潰訪問前值：

if(listEvent.size() > 1 && requestCount <= listEvent.get(1).getTotal())

來源

2016-03-13 08:02:38

但它會使它崩潰。我們不能在以前檢查尺寸嗎？如果我檢查這樣的大小if（listEvent.size（）> = 1 && requestCount <= listEvent.get（1）.getTotal（）它會讓我在我的回收視圖中加載雙重數據 –

我想要的實際頁面限制json。這是getTotal中的頁面限制，所以每個項目都有頁面限制，但我只想使用1項 –

請檢查我的更新，並讓我知道它是否需要 –

它清楚地說：您嘗試訪問列表中不存在元素的第2個元素。您應該在訪問列表之前檢查列表的大小。可以如下檢查：

if(listEvent.size()>= 2 && requestCount <= listEvent.get(1).getTotal()) { 
     requestCount++; 
    }

PS：

我認爲通過使用 獲得（1）你打算訪問的第二個元素。如果你想訪問第一個元素，你應該使用** .get（0）**來代替。

來源

2016-03-13 08:16:10

索引超出界限時調用arraylist中的一個項目

回答

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