通过服务器更新 Listview 并显示更新后的列表视图而不连接

Question

大家好，我已经面临这个问题很多天了，但在谷歌上没有找到正确的解决方案。我想创建一个与我的服务器同步的聊天应用程序我已经实现了一种技术，该技术每 8 秒后从服务器获取数据并在列表视图中显示更新的数据并清除前一个数据。我面临的问题是，当我滚动列表视图时，它会使应用程序崩溃并显示我在 logcat 中发布的错误。

Logcat：

java.lang.IndexOutOfBoundsException: Invalid index 13, size is 0

MainActivity.java

import java.util.ArrayList;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.annotation.RequiresApi;
import android.text.Html;
import android.text.SpannableString;
import android.text.SpannableStringBuilder;
import android.text.style.ForegroundColorSpan;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;  
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.android.volley.Request;
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.JsonObjectRequest;
import com.android.volley.toolbox.StringRequest;
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.HashMap;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;


public class MainActivity extends ListActivity
{
Handler h;int delay;
private static final String REGISTER_URL =  "http://friends.ueuo.com/chat.php";
public static final String RECEVIE_URL = "http://friends.ueuo.com/rec.php";
String message,Sender_name;
public static final String KEY_SEND = "send";
public static final String KEY_RECEIVE = "receive";
public static final String KEY_MESSAGE = "Message";

ArrayList<String> list = new ArrayList<String>();
ArrayList<String> list1 = new ArrayList<String>();
ArrayAdapter<String> adapter,adapter1;

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

     h = new Handler();
    delay = 15000; //milliseconds

    h.postDelayed(new Runnable()
    {
        public void run()
        {
            list.clear();
            Receive();
            h.postDelayed(this, delay);

        }
    }, delay);






    Button btn = (Button) findViewById(R.id.addItem);
    adapter = new ArrayAdapter<String>(this,R.layout.my_custom_layout,  list);

    OnClickListener listener = new OnClickListener()
    {
        @RequiresApi(api = Build.VERSION_CODES.KITKAT)
        @Override
        public void onClick(View v) {
            EditText edit = (EditText) findViewById(R.id.text);
            message = edit.getText().toString();
            String sender = "Sender"+System.lineSeparator()+"";
            list.add(sender+edit.getText().toString());
            setListAdapter(adapter);
            adapter.notifyDataSetChanged();
            registerUser();
        }
    };


    btn.setOnClickListener(listener);


}





private void registerUser()
{


    StringRequest stringRequest = new StringRequest(Request.Method.POST, REGISTER_URL,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    Toast.makeText(MainActivity.this, response, Toast.LENGTH_LONG).show();
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Toast.makeText(MainActivity.this, error.toString(), Toast.LENGTH_LONG).show();
                }
            }) {
        @Override
        protected Map<String, String> getParams() {
            Map<String, String> params = new HashMap<String, String>();
            params.put(KEY_SEND, "ad@gmail.com");
            params.put(KEY_RECEIVE, "bv@gmail.com");
            params.put(KEY_MESSAGE, message);
            return params;
        }

    };

    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);
}




private void Receive()
{


    StringRequest stringRequest = new StringRequest(RECEVIE_URL, new Response.Listener<String>()
    {
        @RequiresApi(api = Build.VERSION_CODES.KITKAT)
        @Override
        public void onResponse(String response)
        {

            showJSON(response);
        }
    },
            new Response.ErrorListener()
            {
                @Override
                public void onErrorResponse(VolleyError error)
                {
                     Toast.makeText(MainActivity.this,error.getMessage().toString(),Toast.LENGTH_LONG ).show();
                }
            });

    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);
}

@RequiresApi(api = Build.VERSION_CODES.KITKAT)
private void showJSON(String response)
{
    JSONObject jsonObject=null;
    JSONArray users = null;
    try
    {
        jsonObject = new JSONObject(response);
        users = jsonObject.getJSONArray("result");

        // JSONObject jsonObject = new JSONObject(response);
        //JSONArray result = jsonObject.getJSONArray("result");
        // JSONObject collegeData = result.getJSONObject(2);
        // name = collegeData.getString("message");
        for(int i=0;i<users.length();i++)
        {

            JSONObject jo = users.getJSONObject(i);
            message=jo.getString("message");
            Sender_name=jo.getString("sendby");
            if (Sender_name.equals("ad@gmail.com"))

            {


                String sender="Wajid Usman"+System.lineSeparator()+"";
                list.add(sender+message);
                setListAdapter(adapter);
                adapter.notifyDataSetChanged();



            }
            else

            {

                String receiver="Salman"+System.lineSeparator()+System.lineSeparator();
                list.add(receiver+message);
                setListAdapter(adapter);
                adapter.notifyDataSetChanged();
            }



        }


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

}

}

Answer 1

这意味着您有 ArrayList，其中有 0 个元素，您可以在其中获取每个元素，例如 0、1、2、ecc 位置。而您正在尝试将第 12 个不存在的元素读入 ArrayList。