我正在研究片段,当我点击一个按钮时,它将转向另一个活动,在活动将数据保存到数据库后,它将返回到片段,但是片段无法显示最新的数据,我需要去片段的活动,然后再回到片段,它会显示最新的数据。
这是我的片段代码。我认为,因为我把setAdapter放在onActivityCreated()方法中,我试着把它放在onCreate()和onCreateView()中,两者都会返回nullpointer错误。
public class TodoFragment extends ListFragment {
private TodoDataSource datasource;
private Todo item;
List<Todo> todoList;
MyCustomAdapter adapt;
ListView listTask;
EditText t;
public TodoFragment(){
}
/*@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
//setHasOptionsMenu(true);
datasource = new TodoDataSource(getActivity());
datasource.open();
todoList = datasource.getAllTodos();
adapt= new MyCustomAdapter(getActivity(), R.layout.todo_list, todoList);
//ListView listTask =(ListView) rootView.findViewById(android.R.id.list);
listTask.setAdapter(adapt);
}*/
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// if (activity != null) {
// Create an instance of the custom adapter for the GridView. A static array of location data
// is stored in the Application sub-class for this app. This data would normally come
// from a database or a web service.
datasource = new TodoDataSource(getActivity());
datasource.open();
todoList = datasource.getAllTodos();
adapt= new MyCustomAdapter(getActivity(), R.layout.todo_list, todoList);
//ListView listTask =(ListView) rootView.findViewById(android.R.id.list);
listTask.setAdapter(adapt);
Button button = (Button) getActivity().findViewById(R.id.simpleadd);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//String summary = t.getText().toString();
Intent i = new Intent(getActivity(), TodoDetailActivity.class);
//Bundle bundle = new Bundle();
// bundle.putString("Summary", summary);
//i.putExtras(bundle);
startActivity(i);
}
});
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.main, menu);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_todo, container, false);
t = (EditText) rootView.findViewById(R.id.simple);
listTask = (ListView) rootView.findViewById(android.R.id.list);
return rootView;
}
@Override
public void onResume() {
datasource.open();
super.onResume();
adapt.notifyDataSetChanged();
}
@Override
public void onPause() {
datasource.close();
super.onPause();
}
}
这是我的另一个活动代码的一部分。 它将更新数据库并返回到片段。
confirmButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (TextUtils.isEmpty(mTitleText.getText().toString())) {
makeToast();
} else {
final String category = mCategory.getSelectedItem().toString();
final String summary = mTitleText.getText().toString();
final String description = mBodyText.getText().toString();
datasource.createTodo(category, summary, description);
setResult(RESULT_OK);
finish();
}
}
});
答案 0 :(得分:0)
在todoList
中致电notifyDataSetChanged()
之前,您似乎没有更新数据来源onResume()
。
编辑:首先清除列表,然后重新填充。还要添加日志记录以帮助追踪问题:
@Override
public void onResume() {
super.onResume();
datasource.open();
todoList.clear();
todoList.addAll(datasource.getAllTodos());
adapt.notifyDataSetChanged();
Log.d("MyApp", "Size of data: " + todoList.size() );
}
添加完该代码后,尝试添加一些记录,然后观察logcat以查看大小是否增加。您还可以遍历每条记录,如果您发布Todo
课程,我可以为您提供一些示例代码。