Question

我有两个片段的活动：DogFragment，LegoFragment。在肖像模式中，我展示了DogFragment，在横向模式中，我展示了LegoFragment。我的问题是碎片在旋转后不记得它们的状态。有没有办法保存片段的状态？了解在方向更改期间重新创建活动，并根据我创建的方向并将DogFragment或LegoFragment附加到活动。

以下是我添加片段的活动的onCreate方法。

@Override 
protected void onCreate(Bundle savedInstanceState) {    
  super.onCreate(savedInstanceState);     
  setContentView(R.layout.activity_main);
   if (getResources().getConfiguration().orientation == 
     Configuration.ORIENTATION_PORTRAIT) { 
   addDogFragment(); 
  } else {
       addLegoFragment();
   }
 }

private void addDogFragment() {
  DogFragment fragment = DogFragment.newInstance(null, null);    
  getSupportFragmentManager().beginTransaction().
  replace(R.id.fragment_container, fragment).commit();
 }  

private void addLegoFragment() {
   LegoFragment fragment = LegoFragment.newInstance(null, null);     
  getSupportFragmentManager().beginTransaction().
  replace(R.id.fragment_container, fragment).commit();
 }

我知道FragmentManager有我的片段的副本。但我不确定解决这个问题的最佳方法。如果我使用标记调用replace，我是否只需找到ByTag然后再次调用replace？或者有一种标准的方法来做这些事情吗？

Answer 1

试试这个，为LegoFragment创建一个类似的功能

private void setDogFragment() {
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    Fragment removeFragment = mFragmentManager.findFragmentByTag("lego");
    if (removeFragment!=null) {
        transaction.detach(removeFragment);
    }
    Fragment fragment = mFragmentManager.findFragmentByTag("dog");
    if (fragment != null) {
        transaction.attach(fragment);
    } else {
        fragment = new DogFragment();
        transaction.add(R.id.fragment_container, fragment,
                "dog");
    }
    transaction.commit();
}

Answer 2

if (getResources().getConfiguration().orientation == 
 Configuration.ORIENTATION_PORTRAIT)
    attachFragment(R.id.fragment_container, "dogFragment",     DogFragment.class.getName());
else 
    attachFragment(R.id.fragment_container, "legoFragment", LegoFragment.class.getName());


private FragmentTransaction mCurTransaction;
private FragmentManager mFragmentManager;
public void attachFragment(int containerViewId, String tag, String fragmentClassName){
    if (mFragmentManager == null)
        mFragmentManager = getSupportFragmentManager(); // or getFragmentManager();

    if (mCurTransaction == null)
        mCurTransaction = mFragmentManager.beginTransaction();

    // Do we already have this fragment?
    Fragment fragment = mFragmentManager.findFragmentByTag(tag);
    if (fragment != null){
        mCurTransaction.attach(fragment);
    }else {
        fragment = Fragment.instantiate(this, fragmentClassName);
        mCurTransaction.add(containerViewId, fragment, tag);
    }
}

屏幕方向更换后如何恢复碎片

2 个答案: