Question

我正在开发一个从服务器获取数据的项目，并在列表视图上显示数据，供用户查看他的工作正常，但在介绍了一个Timer任务来刷新listview的内容后，我得到了很长的无限重复的内容。这是一个屏幕截图，代码正在使用：

package com.example.pius;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.Html;
import android.text.Spanned;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class viewChat extends Activity {
// ArrayList of type "Person". We are making not a list of string, sondern eine list of persons
    ArrayList<Person> arrayOfWebData = new ArrayList<Person>();
class Person{
    public String message;
    public String name;
    public String time;
    //public String last_m;
}
//update stuffs
Timer autoUpdate;

// This is our new Adapter:
    FancyAdapter aa = null;

    // For each row we returned until we use the array to create our person obj
    static ArrayList<String> resultRow;

Intent i;
String rName,recId,myName;
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.chat);
    new getChat().execute();
}

//getting your getting chat with a user from server

    // Params,Progress,Result
        private class getChat extends AsyncTask<Void,Void,Void>
        {
            @Override
            protected Void doInBackground(Void... arg0) {
                String result = "";
                try{
                    HttpClient httpClient = new DefaultHttpClient();
                    HttpPost httpPost = new HttpPost("http://myurl.com/someparams");
                    HttpResponse httpResponse = httpClient.execute(httpPost);
                    HttpEntity httpEntity = httpResponse.getEntity();
                    InputStream is = httpEntity.getContent();
                    // Convert response to String:
                    try{
                        BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
                        StringBuilder sb = new StringBuilder();
                        String line = null;

                        while((line = reader.readLine()) != null){
                            sb.append(line+"\n");
                        }
                        is.close();
                        result = sb.toString();
                    }catch(Exception e){
                        e.printStackTrace();
                    }
                }catch(Exception e){
                    e.printStackTrace();
                }
                // Parse JSON:
                try{
                    JSONArray jArray = new JSONArray(result);
                    for(int i = 0;i < jArray.length();i++)
                    {
                        // Get our object, this is on persons data:
                        JSONObject json_data = jArray.getJSONObject(i);
                        // Create a new person:
                        Person resultRow = new Person();
                        // Set thats persons attributes:
                        resultRow.message = json_data.getString("mmm");
                        resultRow.name = json_data.getString("sss");
                        resultRow.time = json_data.getString("ttt");
                        //resultRow.birthday = json_data.getString("pix");
                        arrayOfWebData.add(resultRow);
                    }   
                }catch(Exception e){
                    e.printStackTrace();
                }
                return null;    
            }
            @Override
            protected void onPostExecute(Void result) {
                // TODO Auto-generated method stub
                super.onPostExecute(result);
                populateListView();
            }   
        }


        public void populateListView()
        {
            final ListView myListView = (ListView)findViewById(R.id.onepm);
            // initialite FancyAdapter object:
            aa = new FancyAdapter();


            myListView.setAdapter(aa);  

            //click action for each list
            myListView.setOnItemClickListener(new AdapterView.OnItemClickListener() 
            {
                @Override
                public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) 
                {
                    // Get Person "behind" the clicked item
                    //Person p = (Person) myListView.getItemAtPosition(position);

                    // Log the fields to check if we got the info we want
                    //Log.i("SomeTag", "Persons name: " + p.person_id);

                    // Do something with the data. For example, passing them to a new Activity
                    //when message is tapped
                }
            }); 




        }


        class FancyAdapter extends ArrayAdapter<Person>
        {
            FancyAdapter(){
                super(viewChat.this,android.R.layout.simple_list_item_1,arrayOfWebData);
                //imageLoader = new ImageLoader(MainActivity.this);
            }
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                final ViewHolder holder;
                if(convertView == null){
                    LayoutInflater inflater = getLayoutInflater();
                    convertView = inflater.inflate(R.layout.row4, parent, false);
                    holder = new ViewHolder(convertView);
                    convertView.setTag(holder); 
                }else{
                    holder = (ViewHolder)convertView.getTag();
                }

                holder.populateFrom(arrayOfWebData.get(position));
                arrayOfWebData.clear();
                return convertView; 
            }
        }

        class ViewHolder
        {
            public TextView name = null;
            public TextView message = null;
            //public TextView time = null;
            //public TextView favorite_color = null;


            ViewHolder(View row){

                name = (TextView)row.findViewById(R.id.opname);
                message = (TextView)row.findViewById(R.id.dmessage);
                //last_m = (TextView)row.findViewById(R.id.lmess);  
            }
            // Notice we have to change our populateFrom() to take an argument of type "Person"
            void populateFrom(Person r){
                if("you".equals(r.name)){
                    //message.setGravity(Gravity.RIGHT);
                RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams)message.getLayoutParams();
                params.setMargins(80, 0, 0, 0);
                message.setLayoutParams(params);
                message.setBackgroundColor(Color.parseColor("#98ccff"));
                }else{
                    //message.setGravity(Gravity.LEFT);
                    RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams)message.getLayoutParams();
                    params.setMargins(0, 0, 80, 0);
                    message.setLayoutParams(params);
                    message.setBackgroundColor(Color.parseColor("#ffcc98"));
                }
                //attempt to bring html to life
                String hdtext = r.message;
                Spanned ftext = Html.fromHtml(hdtext);
               // name.setText(r.name);
                message.setText(ftext);
                //last_m.setText(r.last_m);
                //favorite_color.setText(r.favorite_color); 
            }   
        }
        //auto refresh
        @Override
        public void onResume(){
            super.onResume();
            autoUpdate = new Timer();
            autoUpdate.schedule(new TimerTask(){
                @Override
                public void run(){
                    runOnUiThread(new Runnable(){
                        public void run(){
                            new getChat().execute();
                        }
                    });
                }
            }, 0,300);
        }

}

Answer 1

- 这里是另一个在每个所需时间更新listview的解决方案

创建处理程序和private Handler yourhandler=new Handler(); Runnable yourrunnable = new Runnable() { @Override public void run() { new YourASynctask.execute(); } }; yourhandler.post(yourrunnable);

- 在 Asynctask 的 Postexecute 方法中粘贴代码yourhandler.postDelayed(yourrunnable, 2000);

- 2000 是您所需的时间 - 只需将上面的代码放入 onresume 方法和。 - 在您的代码中，在添加数组之前清除数组。

try{


 arrayweb.clear();

for(...)

{

arrayweb.add(obj);

}

谢谢如果你发现它有用而且如果你仍然卡住了我的回答请告诉我！

android TimerTask不断向listview添加无限项

1 个答案: