我有一个活动,它在 onCreate 中加载一个片段,如下所示:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
loadFragment(new FragmentName());
}
private void loadFragment(Fragment fragment) {
FragmentManager fm = getFragmentManager();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
// replace the FrameLayout with new Fragment
fragmentTransaction.replace(R.id.frag_lay, fragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
我正在尝试保存和恢复加载的片段的状态,如下所示:
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (savedInstanceState != null) {
spinner.setSelection(savedInstanceState.getInt("spinner"));
}
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("spinner", spinner.getSelectedItemPosition());
}
发生的情况是我正确存储了微调器的位置,但无论如何都会重新创建微调器,并且它的位置是默认位置,即使我选择了保存的位置。我不确定为什么会发生这种情况,有人可以帮忙吗?
编辑
我在这里设置微调器:
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_campus, container, false);
...
setupSpinner();
return view;
}
private void setupSpinner() {
ArrayAdapter<CharSequence> adapter =
ArrayAdapter.createFromResource(this.getActivity(),
R.array.array_spinner,
android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter)
}
编辑 2
我又做了一些尝试。我举了一些祝酒词来展示发生的事情是这样的:
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (savedInstanceState != null) {
Toast toast = Toast.makeText(getActivity(), "saved !=", Toast.LENGTH_SHORT);
toast.show();
}else{
Toast toast = Toast.makeText(getActivity(), "saved ==", Toast.LENGTH_SHORT);
toast.show();
}
}
当我尝试在模拟器上运行此代码时,会发生这种情况:当我第一次启动应用程序时,它会进入 else 语句(应该是正确的)。当我改变方向时,两个 toast 都会显示(显然我首先在 onSaveInstanceState 中保存了一些东西),这是不对的。为什么会这样?