Question

我试图在onViewCreated

上创建一个if语句

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);


    date = (TextView) view.findViewById(R.id.textDate);
    date.setText(DateFormat.getDateTimeInstance().format(Calendar.getInstance().getTime()));
}

如果视图是第一次，请设置这两行：

date = (TextView) view.findViewById(R.id.textDate);
        date.setText(DateFormat.getDateTimeInstance().format(Calendar.getInstance().getTime()));

我是否有其他方法可能没有想到和错过，或者if语句是更可行的方法。

以下是代码的其余部分：

public class Notifications extends Fragment {
TextView servingqueue;
TextView date;


DatabaseReference mRootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference mServingQueue = mRootRef.child("ServingQueue");


public Notifications() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);



    mServingQueue.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Double number = dataSnapshot.getValue(Double.class);
            servingqueue.setText(String.valueOf(number));

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

@Override
public void onAttach(Context context) {
    super.onAttach(context);

}

@Override
public void onDetach() {
    super.onDetach();

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_notifications, container, false);
    // Inflate the layout for this fragmentid.queueServing);
    servingqueue = (TextView) rootView.findViewById(R.id.queueServing);
    return rootView;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);


    date = (TextView) view.findViewById(R.id.textDate);
    date.setText(DateFormat.getDateTimeInstance().format(Calendar.getInstance().getTime()));
}

}

Answer 1

如果您只想将设置为第一个时间，则可以检查savedInstanceState是否为空。如果它为空，则整个Fragment都是新品牌。如果它不为空，那么您将从屏幕旋转或其他内容返回。

但是，你的TextView会突然变空，因为它会被创建，所以这是另一种选择。

在onSaveInstanceState中，保存TextView的状态，

@Override
public void onSaveInstanceState(Bundle b) {
   super.onSaveInstanceState(b);
   b.putString("DATE_TEXT", date.getText().toString());
}

然后，在onViewCreated()中，检索文字如下：

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
   super.onViewCreated(view, savedInstanceState);

   String dateText = (savedInstanceState != null) ? 
          savedInstanceState.getString("DATE_TEXT") :
          DateFormat.getDateTimeInstance().format(Calendar.getInstance().getTime());

   date = (TextView) view.findViewById(R.id.textDate);
   date.setText(DateFormat.getDateTimeInstance().format(Calendar.getInstance().getTime()));
}

在onCreateView上的if语句用于第一个视图

1 个答案: