动态刷新listview中的数据

转自：http://www.cnblogs.com/ProgramBull/archive/2012/02/06/2340401.html

之前一直困扰listview刷新后位置的问题，现在才明白，原来不能重新设置listview的adapter，而应该用notifyDataSetChanged()来刷新，这样位置就不会置顶。

下面做了一个测试的例子，点击最后一条记录，会增加一条新的记录。

代码如下：

1.TestAdapter

package com.TestAdapter;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.AdapterView;import android.widget.AbsListView.OnScrollListener;import android.widget.AdapterView.OnItemClickListener;import android.widget.AdapterView.OnItemSelectedListener;import android.widget.AbsListView;import android.widget.ImageView;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.TextView;import android.widget.Toast;public class TestAdapter extends Activity {    /** Called when the activity is first created. */    private int[] images ;    private ListView listview;    private MyAdapter adapter;    List<Map<String,Integer>> al;        @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        images =  new int[]{android.R.drawable.ic_btn_speak_now,                android.R.drawable.alert_light_frame,                android.R.drawable.arrow_down_float,                android.R.drawable.arrow_up_float,                android.R.drawable.btn_star_big_off,                android.R.drawable.btn_star_big_on,                android.R.drawable.button_onoff_indicator_off,                android.R.drawable.button_onoff_indicator_on,                android.R.drawable.checkbox_off_background,                android.R.drawable.checkbox_on_background,                android.R.drawable.ic_btn_speak_now,                android.R.drawable.ic_delete};        listview = (ListView)findViewById(R.id.listview);        al = new ArrayList<Map<String,Integer>>();        for(int i=0; i<12; i++){            HashMap<String,Integer > map = new HashMap<String,Integer>();            map.put(""+i, images[i]);            al.add(map);        }        adapter = new MyAdapter(this, al, R.layout.list_item, new String[]{"imageview", "tv"},                 new int[]{R.id.imageview, R.id.tv});        listview.setAdapter(adapter);        listview.setOnItemClickListener(new OnItemClickListener() {            public void onItemClick(AdapterView<?> arg0, View arg1, int count,                    long arg3) {                if(adapter.getCount()==count+1){                    HashMap<String ,Integer> map = new HashMap<String, Integer>();                    map.put(""+(adapter.mItemList.size()), android.R.drawable.ic_dialog_email);                    al.add(map);                    adapter.mItemList = al;                    adapter.notifyDataSetChanged();                    Toast.makeText(TestAdapter.this, "正在刷新", Toast.LENGTH_SHORT).show();                }                            }        });            }            private class MyAdapter extends SimpleAdapter{        int count = 0;        private List<Map<String, Integer>> mItemList;        public MyAdapter(Context context, List<? extends Map<String, Integer>> data,                int resource, String[] from, int[] to) {            super(context, data, resource, from, to);            mItemList = (List<Map<String, Integer>>) data;            if(data == null){                count = 0;            }else{                count = data.size();            }        }        public int getCount() {            return mItemList.size();        }        public Object getItem(int pos) {            return pos;        }        public long getItemId(int pos) {            return pos;        }                @Override        public View getView(int position, View convertView, ViewGroup parent) {            Map<String ,Integer> map = mItemList.get(position);            int image  =  map.get(""+position);            View view = super.getView(position, convertView, parent);            ImageView imageview = (ImageView)view.findViewById(R.id.imageview);            TextView tv = (TextView)view.findViewById(R.id.tv);            imageview.setBackgroundResource(image);            tv.setText(""+position);            return view;        }    }}

2.main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    >    <ListView android:id="@+id/listview"        android:layout_width="fill_parent"        android:layout_height="wrap_content"    ></ListView>    </LinearLayout>

3.list_item.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    >    <ImageView     android:id="@+id/imageview"    android:layout_width="wrap_content"    android:layout_height="wrap_content">    </ImageView>    <TextView        android:id="@+id/tv" android:layout_width="fill_parent"        android:layout_height="wrap_content"    ></TextView></LinearLayout>