动态更新listView

原文地址：http://www.pocketdigi.com/20100827/75.html

notifyDataSetChanged() 动态更新ListView 通过 Handler AsyncTask两种方式

有时候我们需要修改已经生成的列表，添加或者修改数据，notifyDataSetChanged()可以在修改适配器绑定的数组后，不用重新刷新Activity，通知Activity更新ListView。今天的例子就是通过Handler AsyncTask两种方式来动态更新ListView.从今天起，每次学习的源代码都会打包上传，方便各位同学学习，注册帐号即可下载。
布局main.xml:

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<?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/lv" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /> </LinearLayout>

ListView列表布局playlist.xml:

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<?xml version="1.0" encoding="utf-8"?> <TextView android:id="@+id/text1" xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="30px" android:textSize="18sp" ></TextView>

程序代码：

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package com.pocketdigi;   import java.util.ArrayList; import android.app.Activity; import android.os.AsyncTask; import android.os.Bundle; import android.os.Handler; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ListView; import android.widget.AdapterView.OnItemClickListener;   public class main extends Activity { /** Called when the activity is first created. */ ListView lv; ArrayAdapter<String> Adapter; ArrayList<String> arr=new ArrayList<String>(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); lv=(ListView)findViewById(R.id.lv); arr.add("123"); arr.add("234"); arr.add("345"); Adapter = new ArrayAdapter<String>(this,R.layout.playlist, arr); lv.setAdapter(Adapter); lv.setOnItemClickListener(lvLis); editItem edit= new editItem(); edit.execute("0","第1项");//把第一项内容改为"第一项" Handler handler=new Handler(); handler.postDelayed(add,3000);//延迟3秒执行 } Runnable add=new Runnable(){   @Override public void run() { // TODO Auto-generated method stub arr.add("增加一项");//增加一项 Adapter.notifyDataSetChanged(); } }; class editItem extends AsyncTask<String,Integer,String>{ @Override protected String doInBackground(String... params) { arr.set(Integer.parseInt(params[0]),params[1]); //params得到的是一个数组，params[0]在这里是"0",params[1]是"第1项" Adapter.notifyDataSetChanged(); return null; } } private OnItemClickListener lvLis=new OnItemClickListener(){ @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { //点击条目时触发 //arg2即为点中项的位置 setTitle(String.valueOf(arr.get(arg2)));   }   };   }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Listview动态加载数据

收藏 分享 2011-3-22 11:30| 发布者: annmax| 查看数: 456| 评论数: 0

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摘要: 最近在研究网络数据加载的问题，比如我有几百，甚至上千条数据，这些数据如果一次性全部加载到arraylist，然后再加载到Listview中。我们必然会去单独开线程来做，这样造成的结果就是会出现等待时间很长，用户体验非 ...

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最近在研究网络数据加载的问题，比如我有几百，甚至上千条数据，这些数据如果一次性全部加载到arraylist，然后再加载到Listview中。我们必然会去单独开线程来做，这样造成的结果就是会出现等待时间很长，用户体验非常不好。我的想法是动态加载数据，第一次加载十条，然后往下面滑动的时候再追加十条，再往下面滑动的时候再去追加，这样大大减少了用户等待的时间，同时给处理数据留下了时间。网上看到了这样一个例子，挺好的，我改动了一下，达到了我想要的结果。 import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.Gravity; import android.view.View; import android.view.ViewGroup; import android.widget.AbsListView; import android.widget.BaseAdapter; import android.widget.LinearLayout; import android.widget.ListView; import android.widget.ProgressBar; import android.widget.TextView; import android.widget.Toast; import android.widget.AbsListView.OnScrollListener; import android.widget.LinearLayout.LayoutParams; public class ListViewForLoading extends Activity implements OnScrollListener {     private listViewAdapter adapter = new listViewAdapter();     ListView listView;     LinearLayout loadingLayout;     private Thread mThread;     /**      * 设置布局显示属性      */     private LayoutParams mLayoutParams = new LinearLayout.LayoutParams(             LinearLayout.LayoutParams.WRAP_CONTENT,             LinearLayout.LayoutParams.WRAP_CONTENT);     /**      * 设置布局显示目标最大化属性      */     private LayoutParams FFlayoutParams = new LinearLayout.LayoutParams(             LinearLayout.LayoutParams.FILL_PARENT,             LinearLayout.LayoutParams.FILL_PARENT);     private ProgressBar progressBar;     /** Called when the activity is first created. */     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);         init();     }     private void init() {         // TODO Auto-generated method stub         // 线性布局         LinearLayout layout = new LinearLayout(this);         // 设置布局 水平方向         layout.setOrientation(LinearLayout.HORIZONTAL);         // 进度条         progressBar = new ProgressBar(this);         // 进度条显示位置         progressBar.setPadding(0, 0, 15, 0);         // 把进度条加入到layout中         layout.addView(progressBar, mLayoutParams);         // 文本内容         TextView textView = new TextView(this);         textView.setText("加载中...");         textView.setGravity(Gravity.CENTER_VERTICAL);         // 把文本加入到layout中         layout.addView(textView, FFlayoutParams);         // 设置layout的重力方向，即对齐方式是         layout.setGravity(Gravity.CENTER);         // 设置ListView的页脚layout         loadingLayout = new LinearLayout(this);         loadingLayout.addView(layout, mLayoutParams);         loadingLayout.setGravity(Gravity.CENTER);         // 得到一个ListView用来显示条目         listView = (ListView) findViewById(R.id.tv);         // 添加到脚页显示         listView.addFooterView(loadingLayout);         // 给ListView添加适配器         listView.setAdapter(adapter);         // 给ListView注册滚动监听         listView.setOnScrollListener(this);     }     /**      * 要用用于生成显示数据      *      * @author huangbq      *      */     class listViewAdapter extends BaseAdapter {         int count = 10;         public int getCount() {             return count;         }         public Object getItem(int pos) {             return pos;         }         public long getItemId(int pos) {             return pos;         }         public View getView(int pos, View v, ViewGroup p) {             TextView view;             if (v == null) {                 view = new TextView(ListViewForLoading.this);             } else {                 view = (TextView) v;             }             view.setText("ListItem " + pos);             view.setTextSize(20f);             view.setGravity(Gravity.CENTER);             view.setHeight(60);             return view;         }     }     @Override     public void onScroll(AbsListView view, int firstVisibleItem,             int visibleItemCount, int totalItemCount) {         // TODO Auto-generated method stub         if(firstVisibleItem+visibleItemCount==totalItemCount)         {             //开线程去下载网络数据             if (mThread == null || !mThread.isAlive()) {                 mThread = new Thread() {                     @Override                     public void run() {                         try {                             //这里放你网络数据请求的方法，我在这里用线程休眠5秒方法来处理                             Thread.sleep(5000);                         } catch (InterruptedException e) {                             e.printStackTrace();                         }                         Message message = new Message();                         message.what = 1;                         handler.sendMessage(message);                     }                 };                 mThread.start();                            }         }     }     @Override     public void onScrollStateChanged(AbsListView view, int scrollState) {         // TODO Auto-generated method stub            }     private Handler handler = new Handler() {         @Override         public void handleMessage(Message msg) {             // TODO Auto-generated method stub             switch (msg.what) {             case 1:                 if (adapter.count <= 41) {                     adapter.count += 10;                     int currentPage = adapter.count / 10;                     Toast.makeText(getApplicationContext(),"第" + currentPage + "页", Toast.LENGTH_LONG).show();                 } else {                     listView.removeFooterView(loadingLayout);                 }                 //重新刷新Listview的adapter里面数据                 adapter.notifyDataSetChanged();                 break;             default:                 break;             }         }     }; } 运行结果如下图：