我有一个创建 ListView
和 Custom Adapter
的主要 Activity 。如果我事先已经创建了 List,我可以填充 ListView
,但是如何使用动态获取的数据填充它?
主 Activity
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;
}
}
项目
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
}
如何修改我的代码,以便后台函数将项目检索到自定义适配器并填充 ListView?我尝试使用 AsyncTask
但无法让它工作。
编辑:在 onCreate()
之后的 MainActivity
中添加了以下 AsyncTask
只是为了测试一下。它的工作原理是我可以看到从 1 到 5 的计数然后完成。
如何让 AsyncTask
更新我的适配器和 ListView
?
onCreate()
应将什么传递给 AsyncTask
以及 AsyncTask
应返回什么?
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!");
}
}
最佳答案
无论何时添加新数据,您都应该这样做:
adapter.notifyDataSetChanged()
例如:
database.insert(data);
myAdapter.notifyDataSetChanged();
或者:
myAdapter.mySetNewContentMethod(someNewContent);
myAdapter.notifyDataSetChanged();
关于android - 如何使用自定义适配器动态更新 ListView?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18395753/