哪位大神帮我看看ListView上的数据不能实时更新

package org.lhm.laofengxiang;

import java.util.*;

import cn.yljd.service.MyXMLParser;

import android.app.Activity;

import android.app.AlertDialog;

import android.app.Dialog;

import android.content.Context;

import android.content.DialogInterface;

import android.os.Bundle;

import android.text.Html;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.view.View.OnClickListener;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.*;

public class Jjtz extends Activity {

MyXMLParser parser=new MyXMLParser();

static int size = 14;

private ListView list;

private MyAdapter myAda;

ArrayList<HashMap<String,Object>> arrayList=new ArrayList<HashMap<String,Object>>();

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.jjtzsummary);

list=(ListView)findViewById(R.id.jjtzlist);

list.setOnItemClickListener(new OnItemClickListener() {

public void onItemClick(AdapterView<?> arg0, View arg1,

int arg2, long arg3) {

myAda.Login(arg2);

}

});

List<String[]> list1=parser.xml2list("http://203.86.16.92:8000/ProduceManager.asmx/selectJjtz", "diffgr:diffgram/NewDataSet/Table", "dm,mc,lsj,dhj");

for(String[] str:list1){

HashMap<String, Object> map = new HashMap<String, Object>();

map.put("dm", str[0]);

map.put("mc", str[1]);

map.put("lsj", str[2].substring(0, str[2].length()-2));

map.put("dhj", str[3].substring(0, str[3].length()-2));

arrayList.add(map);

myAda = new MyAdapter(this, arrayList, size);

list.setAdapter(myAda);

myAda.notifyDataSetChanged();

}

ZoomControls zoomControls = (ZoomControls) findViewById(R.id.zoomcontrols);

zoomControls.setOnZoomInClickListener(new OnClickListener() {

public void onClick(View v) {

size = size + 2;

myAda = new MyAdapter(Jjtz.this, arrayList, size);

list.setAdapter(myAda);

myAda.notifyDataSetChanged();

}

});

zoomControls.setOnZoomOutClickListener(new OnClickListener() {

public void onClick(View v) {

size = size - 2;

myAda = new MyAdapter(Jjtz.this, arrayList, size);

list.setAdapter(myAda);

myAda.notifyDataSetChanged();

}

});

}

private class MyAdapter extends BaseAdapter {

ArrayList<HashMap<String, Object>> data;

Context context;

int size;

public MyAdapter(Context context,

ArrayList<HashMap<String, Object>> data, int size) {

this.context = context;

this.data = data;

this.size = size;

}

public int getCount() {

return data.size();

}

public Object getItem(int position) {

return data.get(position);

}

public long getItemId(int position) {

return position;

}

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

LayoutInflater inflater = LayoutInflater.from(context);

convertView = inflater.inflate(R.layout.jjtzsummaryresult, null);

TextView dm = (TextView) convertView.findViewById(R.id.dm);

TextView mc = (TextView) convertView.findViewById(R.id.mc);

TextView lsj = (TextView) convertView.findViewById(R.id.lsj);

TextView dhj = (TextView) convertView.findViewById(R.id.dhj);

dm.setTextSize(size);

mc.setTextSize(size);

lsj.setTextSize(size);

dhj.setTextSize(size);

dm.setText(data.get(position).get("dm").toString());

mc.setText(data.get(position).get("mc").toString());

lsj.setText(data.get(position).get("lsj").toString());

dhj.setText(data.get(position).get("dhj").toString());

return convertView;

}

public void Login(final int arg2) {

LayoutInflater factory=LayoutInflater.from(Jjtz.this);

final View v1=factory.inflate(R.layout.jjtzdialog,null);

AlertDialog.Builder dialog=new AlertDialog.Builder(Jjtz.this);

dialog.setTitle("修改金价");

dialog.setView(v1);

dialog.setPositiveButton("确定修改", new DialogInterface.OnClickListener() {

public void onClick(DialogInterface dialog, int whichButton) {

//修改金价

try{

EditText lsj=(EditText) v1.findViewById(R.id.lsj);

EditText dhj=(EditText) v1.findViewById(R.id.dhj);

String lsjStr = lsj.getText().toString().trim();

String dhjStr = dhj.getText().toString().trim();

String dm=data.get(arg2).get("dm").toString();

List<String[]> list=parser.xml2list("http://203.86.16.92:8000/ProduceManager.asmx/updateJjtz?lsj="+lsjStr+"&dhj="+dhjStr+"&dm="+dm+"", "diffgr:diffgram", "");

}catch(Exception e){

e.printStackTrace();

}

}

});

dialog.setNegativeButton("取消修改",new DialogInterface.OnClickListener() {

public void onClick(DialogInterface dialog, int which) {

}

});

dialog.show();

}

}

}