ListView优化实战指南

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">这里有几个关键字：ListView && GridView</span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">几乎每个android App应该都可以看到ListView或者GridView的影子，如果你是一个android开发者，你肯定对ListView又爱又恨！</span>

下面我们就一些具体的代码讲一讲怎么优化ListView：
Terminology

>index (索引)
>position(位置)
>id（标识）

Stable IDs
>hasStableIds() == true
>An ID always refers to the same value
>Helps ListView

adapter
getView


listview is smart


contentView
>supplied by listview
>matcher item types
>reuse it


 主布局代码：activity_list.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="${relativePackage}.${activityClass}" >    <ListView        android:id="@+id/mListview"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></RelativeLayout>

icon_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:gravity="center"    android:orientation="horizontal" >    <ImageView        android:id="@+id/item_icon"        android:layout_width="40dp"        android:layout_height="40dp"        android:layout_marginLeft="16dp"        android:src="@drawable/flag_uk" />    <TextView        android:id="@+id/item_text"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_marginRight="16dp"        android:layout_weight="1"        android:gravity="center"        android:text="delfaut text" /></LinearLayout>

ListActivity.java

package com.pdsu.customview;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import com.pdsu.customview.utils.MyAdapter;import com.pdsu.customview.utils.ToastUtils;import android.app.Activity;import android.os.Bundle;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.ListView;import android.widget.Toast;public class ListActivity extends Activity {private List<Map<String, String>> lists = null;private ListView mListView;private LayoutInflater mInflater;private MyAdapter adapter;private ToastUtils mToast;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_list);lists = new ArrayList<Map<String, String>>();mInflater = this.getLayoutInflater();mToast=new ToastUtils();getData();mListView = (ListView) findViewById(R.id.mListview);adapter = new MyAdapter(this, mInflater, lists);mListView.setAdapter(adapter);mListView.setOnItemClickListener(new OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> parent, View view, int position, long id) {// TODO Auto-generated method stubif (lists.get(position).get("image") == "0") {lists.get(position).put("image", "1");} else {lists.get(position).put("image", "0");}// Toast.makeText(getApplicationContext(), "图片改变了！", 0).show();mToast.showToast(getApplicationContext(), "图片改变了！"+lists.get(position).get("sno"));adapter.notifyDataSetChanged();}});}private void getData() {// TODO Auto-generated method stubfor (int i = 0; i < 1000; i++) {Map<String, String> maps = new HashMap<String, String>();maps.put("sno", "s" + i);maps.put("image", "0");lists.add(maps);}}}

package com.pdsu.customview.utils;import java.util.List;import java.util.Map;import com.pdsu.customview.R;import android.R.layout;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.TextView;public class MyAdapter extends BaseAdapter {private List<Map<String, String>> lists = null;private Context mContext;public MyAdapter(Context mContext, LayoutInflater mInflater, List<Map<String, String>> lists) {super();this.mContext = mContext;this.mInflater = mInflater;this.lists = lists;}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn lists == null ? 0 : lists.size();}@Overridepublic Object getItem(int position) {// TODO Auto-generated method stubif (lists == null) {return "数据项为空";} else {return lists.get(position);}}@Overridepublic long getItemId(int position) {// TODO Auto-generated method stubreturn 0;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {// TODO Auto-generated method stubViewHolder holder = null;if (convertView == null) {convertView = mInflater.inflate(R.layout.icon_item, parent, false);holder = new ViewHolder();holder.text = (TextView) convertView.findViewById(R.id.item_text);holder.icon = (ImageView) convertView.findViewById(R.id.item_icon);convertView.setTag(holder);} else {holder = (ViewHolder) convertView.getTag();}holder.text.setText(lists.get(position).get("sno"));holder.icon.setImageResource(lists.get(position).get("image") == "0" ? R.drawable.flag_uk : R.drawable.flag_us);return convertView;}private LayoutInflater mInflater;static class ViewHolder {TextView text;ImageView icon;}}

package com.pdsu.customview.utils;import android.content.Context;import android.widget.Toast;public class ToastUtils {private static Toast mToast = null;public void showToast(Context mContext, String msg) {if (mToast == null) {mToast = Toast.makeText(mContext, msg, Toast.LENGTH_SHORT);} else {mToast.setText(msg);}mToast.show();}}

源码地址：http://download.csdn.net/detail/osevenblue/9294785