Android ViewModel无法在片段更改后继续存在

Question

我一直在尝试使用viewmodel和livedata来分享片段之间的信息.

但是当我从第一个片段更改为另一个片段时,我的viewmodel似乎重新初始化,使我丢失了以前存储的所有数据.

我在我的片段中以相同的方式获得了两次我的viewmodel:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    interventionViewModel = ViewModelProviders.of(this).get(InterventionsViewModel.class);

}

这就是我在我的活动中替换我的framgents的方式(我猜问题必须来自片段生命周期,但我无法弄清楚错误在哪里:/)

public void showFragment(Fragment fragment) {

    String TAG = fragment.getClass().getSimpleName();
    FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
    fragmentTransaction.replace(R.id.fragment_container, fragment, TAG);
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commitAllowingStateLoss();
}

public void backstackFragment() {
    Log.d("Stack count", getSupportFragmentManager().getBackStackEntryCount() + "");
    if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
        finish();
    }
    getSupportFragmentManager().popBackStack();
    removeCurrentFragment();
}

private void removeCurrentFragment() {
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    Fragment currentFrag = getSupportFragmentManager()
            .findFragmentById(R.id.fragment_container);

    if (currentFrag != null) {
        transaction.remove(currentFrag);
    }
    transaction.commitAllowingStateLoss();
}

当我需要一个片段时,我会调用backStackFragment()删除当前片段然后调用showFragment(MyFragment.newInstance());

该片段是AndroidStudio生成的片段

谢谢你的帮助,

亲切的,Matthieu

Answer 1

尝试绑定到活动而不是当前片段.

interventionViewModel = ViewModelProviders.of(activity).get(InterventionsViewModel.class);