面试中经常问到listView优化的问题，个人回答主要如下
1、View重用 使用setTag把view缓存起来
2、适配器在主线程修改
3、在主线程提交适配器的变化，并调用notifyDataSetChanged()方法
4、可以在任何地方获取数据，但应该在另外一个地方请求数据，数据多次请求分次显示
简单实例:
package com.android.listviewtest;
import java.util.LinkedHashMap;
import java.util.Map;
import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
//定义view缓存对象
static class HolderView {
TextView showName;
TextView showInfo;
}
//一次装载 多次显示
private Map<String, String> maps;
// 显示的页数
private int page = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
maps=new LinkedHashMap<String, String>();
for (int i = 0; i < 100; i++) {
maps.put("熊"+i, "程序员"+i+"号");
}
Button btshow = (Button) findViewById(R.id.bt_show);
ListView showlist = (ListView) findViewById(R.id.listshow);
final ShowName showName = new ShowName();
showlist.setAdapter(showName);
btshow.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (page< 100 / 5) {
page++;
showName.notifyDataSetChanged();
}else{
Toast.makeText(MainActivity.this, "没有多余的数据了", Toast.LENGTH_LONG).show();
}
}
});
}
class ShowName extends BaseAdapter {
// 每次加载5条数据
@Override
public int getCount() {
return page * 5;
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
HolderView holderView;
//判断每一个item中的view是否已经存在
if (convertView == null) {
//加载view
convertView = LayoutInflater.from(MainActivity.this).inflate(
R.layout.show_name, null);
holderView = new HolderView();
holderView.showName = (TextView) convertView
.findViewById(R.id.txt1);
holderView.showInfo = (TextView) convertView
.findViewById(R.id.txt2);
//添加一个额外的数据
convertView.setTag(holderView);
} else {
holderView = (HolderView) convertView.getTag();
}
String name=((maps.keySet().toArray())[position]).toString();
String info=maps.get(name);
holderView.showName.setText(name);
holderView.showInfo.setText(info);
return convertView;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}