Question

我按照以下方式在framelayout中添加了片段

    mUserListFragment = new UserListFragment();
    mMessageFragment = new MessageFragment();
    mAccountFragment = new AccountFragment();

    fragmentManager.beginTransaction().add(R.id.frame_layout, mAccountFragment, mAccountFragment.getClass().getSimpleName()).addToBackStack(mAccountFragment.getClass().getSimpleName()).commit();
    fragmentManager.beginTransaction().add(R.id.frame_layout, mMessageFragment, mMessageFragment.getClass().getSimpleName()).addToBackStack(mMessageFragment.getClass().getSimpleName()).commit();
    fragmentManager.beginTransaction().add(R.id.frame_layout, mUserListFragment, mUserListFragment.getClass().getSimpleName()).addToBackStack(mUserListFragment.getClass().getSimpleName()).commit();

稍后我会以以下方式显示或隐藏片段

//for showing
fragmentManager.beginTransaction().show(fragment).commit();

//for hiding 
fragmentManager.beginTransaction().hide(fragment).commit();

从片段的其中一个，我通过一些onClick方法转到另一个Activity，然后该Activity重定向到保存这些片段的同一活动。回到片段持有者的活动时，我将片段重新加载到onResume中，但它使该片段为空白，但是通过调试，我知道片段可见，并且调用了onCreateView方法，我尝试按照以下方式重新加载片段

FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();

ft.setReorderingAllowed(false);

ft.detach(activeFragment).commitNow();
ft.attach(activeFragment).commitNow();

我也尝试过

fragmentManager.beginTransaction().detach(activeFragment).attach(activeFragment).commitAllowingStateLoss();

所有这些都只留下空白屏幕。

Answer 1

您可以通过以下代码跟踪片段的堆栈和片段计数。

getSupportFragmentManager().addOnBackStackChangedListener(new OnBackStackChangedListener() {
            public void onBackStackChanged() {
                Log.i(TAG, "back stack changed ");
                int backCount = getSupportFragmentManager().getBackStackEntryCount();

                // you can also track which are current fragments are in stack by
                getSupportFragmentManager().getFragments();

                if(backCount ==0){

                    //then you have to check whats going wrong in your case
                    // suppose to kill current activity also by finish();
                    // I means its depending on your requirements.


                }

            }
        });

它将帮助您找到自己的出路。

Answer 2

您需要通过newInstanse（）方法创建片段。

public class YourFragment extends Fragment {

    public static YourFragment newInstance() {
        Bundle args = new Bundle();
        YourFragment fragment = new YourFragment();
        fragment.setArguments(args);
        return fragment;
    }
}

活动中：

getSupportFragmentManager()
  .beginTransaction()
  .replace(R.id.content,YourLoanFragment.newInstance(),tag)
  .commit();

重新加载片段使黑屏

2 个答案: