如何动态更新与自定义适配器的ListView？ [英] How to dynamically update a ListView with custom adapter?
问题描述
我有一个创建一个的ListView 和自定义适配器主要活动。我能够填充的ListView 如果我已经预先创建，但列表如何填充它与动态获取的数据？
MainActivity
公共类MainActivity延伸活动{
私人的ListView myListView;
私人上下文CTX;
@覆盖
公共无效的onCreate（包savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.MainActivity）;
CTX =这一点;
名单＆LT;项目＆GT; myList上=新的ArrayList＆LT;项目＆GT;（）;
myList.add（新项目（名1，说明1））;
myList.add（新项目（名2，说明2））;
myList.add（新项目（3名，说明3））;
myList.add（新项目（4名，说明4））;
myList.add（新项目（5名，说明5））;
myListView =（ListView控件）findViewById（R.id.list）;
MyListAdapter myAdapter =新MyListAdapter（CTX，R.layout.listitem，myList中）;
myListView.setAdapter（myAdapter）;
}
}
MyListAdapter
公共类MyListAdapter扩展ArrayAdapter＆LT;项目＆GT; {
私人诠释的资源;
私人LayoutInflater mLayoutInflater;
公共MyListAdapter（上下文CTX，INT RESOURCEID，列表和LT;项目＆GT;对象）{
超（CTX，RESOURCEID，对象）;
资源= RESOURCEID;
mLayoutInflater = LayoutInflater.from（CTX）;
}
@覆盖
公共查看getView（INT位置，查看convertView，ViewGroup中父）{
convertView =（RelativeLayout的）mLayoutInflater.inflate（资源，NULL）;
项目项目=（产品）的getItem（位置）;
TextView的txtName的=（的TextView）convertView.findViewById（R.id.listName）;
txtName.setText（item.getName（））;
TextView的txtDesc =（TextView中）convertView.findViewById（R.id.listDescription）;
txtDesc.setText（item.getDesc（））;
返回convertView;
}
}
项目
公共类项目{
私人字符串名称;
私人字符串说明;
公共项目（字符串名称，字符串DESC）{
超（）;
this.name =名称;
this.desc =说明;
}
// getter和setter
}
如何修改我的code，使得在后台函数检索项自定义适配器和填充的ListView？我试图使用的AsyncTask ，但不能设法得到它的工作。
修改：添加了以下的AsyncTask 在 MainActivity 在的onCreate（）只是为了测试的事情了。它的工作中，我可以看到的计数从1到5，然后完成。
我如何获得的AsyncTask 来更新我的适配器和的ListView 虽然？
我应该的onCreate（）传递给的AsyncTask 又该的AsyncTask 返回？
私有类GetItems扩展的AsyncTask＆LT;太虚，整型，太虚＆GT; {
@覆盖
在preExecute保护无效（）{
super.on preExecute（）;
TextView的myMsg =（TextView中）findViewById（R.id.topMsg）;
myMsg.setText（载入中...）;
}
@覆盖
保护无效doInBackground（虚空...... PARAMS）{
TextView的myMsg =（TextView中）findViewById（R.id.topMsg）;
的for（int i = 1; I＆LT; = 5;我++）{
尝试 {
视频下载（1000）;
publishProgress（ⅰ）;
}赶上（InterruptedException异常E）{
}
}
返回null;
}
保护无效onProgressUpdate（整数...值）{
TextView的myMsg =（TextView中）findViewById（R.id.topMsg）;
myMsg.setText（Integer.toString（值[0] .intValue（）））;
}
@覆盖
保护无效onPostExecute（无效的结果）{
TextView的myMsg =（TextView中）findViewById（R.id.topMsg）;
myMsg.setText（完成！）;
}
}
当你添加新的数据，你应该这样做：
adapter.notifyDataSetChanged（）
例如：
database.insert（数据）;
myAdapter.notifyDataSetChanged（）;
I have a main activity that creates a ListView and a Custom Adapter. I'm able to populate the ListView if I have the List already created beforehand, but how do I populate it with dynamically fetched data?
MainActivity
public class MainActivity extends Activity {
private ListView myListView;
private Context ctx;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.MainActivity);
ctx = this;
List<Items> myList = new ArrayList<Items>();
myList.add(new Item("Name 1", "Desc 1"));
myList.add(new Item("Name 2", "Desc 2"));
myList.add(new Item("Name 3", "Desc 3"));
myList.add(new Item("Name 4", "Desc 4"));
myList.add(new Item("Name 5", "Desc 5"));
myListView = (ListView)findViewById(R.id.list);
MyListAdapter myAdapter = new MyListAdapter(ctx,R.layout.listitem, myList);
myListView.setAdapter(myAdapter);
}
}
MyListAdapter
public class MyListAdapter extends ArrayAdapter<Items> {
private int resource;
private LayoutInflater mLayoutInflater;
public MyListAdapter ( Context ctx, int resourceId, List<Items> objects) {
super( ctx, resourceId, objects );
resource = resourceId;
mLayoutInflater = LayoutInflater.from( ctx );
}
@Override
public View getView ( int position, View convertView, ViewGroup parent ) {
convertView = ( RelativeLayout ) mLayoutInflater.inflate( resource, null );
Items item = (Items) getItem( position );
TextView txtName = (TextView) convertView.findViewById(R.id.listName);
txtName.setText(item.getName());
TextView txtDesc = (TextView) convertView.findViewById(R.id.listDescription);
txtDesc.setText(item.getDesc());
return convertView;
}
}
Item
public class Item {
private String name;
private String desc;
public Item(String name, String desc) {
super();
this.name = name;
this.desc = desc;
}
//getters and setters
}
How can I modify my code such that a function in the background retrieves the items to the custom adapter and populates the ListView? I tried using an AsyncTask but couldn't manage to get it to work.
Edit: Added the following AsyncTask in MainActivity after onCreate() just to test things out. It's working in that I can see the counting from 1 to 5 and then done.
How do I get the AsyncTask to update my adapter and ListView though?
What should onCreate() pass to the AsyncTask and what should AsyncTask return?
private class GetItems extends AsyncTask<Void, Integer, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
TextView myMsg = (TextView)findViewById(R.id.topMsg);
myMsg.setText("Loading...");
}
@Override
protected Void doInBackground(Void... params) {
TextView myMsg = (TextView)findViewById(R.id.topMsg);
for (int i=1;i<=5;i++) {
try {
Thread.sleep(1000);
publishProgress(i);
} catch (InterruptedException e) {
}
}
return null;
}
protected void onProgressUpdate(Integer... values) {
TextView myMsg = (TextView)findViewById(R.id.topMsg);
myMsg.setText(Integer.toString(values[0].intValue()));
}
@Override
protected void onPostExecute(Void result) {
TextView myMsg = (TextView)findViewById(R.id.topMsg);
myMsg.setText("Done!");
}
}
Whenever you add new data you should do this:
adapter.notifyDataSetChanged()
For example:
database.insert(data);
myAdapter.notifyDataSetChanged();
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