Question

我需要在onResume函数中更新我的List View，问题是我的视图在那里是null：

mList = (ListView) v.findViewById(R.id.list); //v is null

我该怎么办？如何获取列表视图以进行更新？

以下是onCreate函数的一部分：

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    View v = findViewById(R.id.large_screen_layout);
    mList = (ListView) v.findViewById(R.id.list);
}

以下是恢复功能：

@Override
protected void onResume() 
{
super.onResume();

mMyBroadcastReceiver = new BroadcastReceiver() {

@Override
public void onReceive(Context context, Intent intent)
{
// Here you can refresh your listview or other UI
String textmessage = intent.getStringExtra("Message");
Toast.makeText(getApplicationContext(), textmessage, Toast.LENGTH_LONG).show();
item = new RowItem(R.drawable.alert_icon, "text1", "text2");
rowItems.add(item);
adapter = new CustomListViewAdapter(getApplicationContext(),R.id.list,rowItems);
adapter.notifyDataSetChanged();
//now either, i need to use view (v) or mList(List View):
mList = (ListView) v.findViewById(R.id.list); //v and mList are NULL here
mList.setAdapter(adapter); 
}
};
try {
LocalBroadcastManager.getInstance(this).registerReceiver(mMyBroadcastReceiver,new     IntentFilter("your_action"));   
} catch (Exception e)
{
            // TODO: handle exception
            e.printStackTrace();
}
}

任何想法如何更新它？

谢谢！

叶兰。

Answer 1

@Override
protected void onResume() 
{
super.onResume();

mMyBroadcastReceiver = new BroadcastReceiver() {

@Override
public void onReceive(Context context, Intent intent)
{
// Here you can refresh your listview or other UI
String textmessage = intent.getStringExtra("Message");
Toast.makeText(getApplicationContext(), textmessage, Toast.LENGTH_LONG).show();
item = new RowItem(R.drawable.alert_icon, "text1", "text2");
rowItems.add(item);
adapter = new CustomListViewAdapter(getApplicationContext(),R.id.list,rowItems);
adapter.notifyDataSetChanged();
//now either, i need to use view (v) or mList(List View):

// need to find V
View v = findViewById(R.id.large_screen_layout);

mList = (ListView) v.findViewById(R.id.list); //v and mList are NULL here
mList.setAdapter(adapter); 

}
};
try {
LocalBroadcastManager.getInstance(this).registerReceiver(mMyBroadcastReceiver,new     IntentFilter("your_action"));   
} catch (Exception e)
{
            // TODO: handle exception
            e.printStackTrace();
}
}

还要确保在onPause中取消注册广播接收器，否则它可能会以意想不到的方式接收通知。

Answer 2

如果您使用活动或 FragmentActivity ，请更改 OnCreate 功能：

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.large_screen_layout);    
    mList = (ListView)findViewById(R.id.list);
}

或者如果您想使用片段

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    view = inflater.inflate(R.layout.large_screen_layout, null);
    mList = (ListView)view.findViewById(R.id.list);

    return view;
}

Answer 3

试试这个：

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
View v = findViewById(R.id.large_screen_layout);
mList = (ListView) v.findViewById(R.id.list);
adapter = new CustomListViewAdapter(getApplicationContext(),
R.id.list,rowItems);
mList.setAdapter(adapter);} 

@Override
protected void onResume() {
    super.onResume();
    mMyBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String textmessage = intent.getStringExtra("Message");
            Toast.makeText(getApplicationContext(), textmessage, Toast.LENGTH_LONG).show();
            item = new RowItem(R.drawable.alert_icon, "text1", "text2");
            rowItems.add(item);
            adapter.notifyDataSetChanged();
        }
    };
    try {
        LocalBroadcastManager.getInstance(this).registerReceiver(mMyBroadcastReceiver, new IntentFilter("your_action"));
    } catch (Exception e) {
        // TODO: handle exception 
        e.printStackTrace();
    }
}

更新列表视图onResume（无法获取视图）

3 个答案: