在片段中加載RetainFragment

Question

您好Android開發者， 我遵循Android Developers的顯示圖像指南，並且想要從RetainFragment加載我的初始化緩存，如果我旋轉我的設備。 A在我的ListFragmentsonActivityCreated()方法中執行此操作，但每次創建新片段並且不重複使用片段。

我做這樣的事情： RetainFragment

class RetainFragment extends Fragment { 
private static final String TAG = "RetainFragment"; 
public LruCache mRetainedCache; 

public RetainFragment() {} 

public static RetainFragment findOrCreateRetainFragment(FragmentManager fm) { 
    RetainFragment fragment = (RetainFragment) fm.findFragmentByTag(TAG); 
    if (fragment == null) { 
     fragment = new RetainFragment(); 
    } 
    return fragment; 
} 

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

}

而且這樣的：ListFragment

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

    RetainFragment mRetainFragment = RetainFragment.findOrCreateRetainFragment(getFragmentManager()); 
    LruCache mMemoryCache = RetainFragment.mRetainedCache; 
    if (mMemoryCache == null) 
    { 
     mMemoryCache = new LruCache(cacheSize); 
     mRetainFragment.mRetainedCache = mMemoryCache; 
    } 
    else 
    { 
     mMemoryCache = mRetainFragment.mRetainedCache; 
    } 
    ... 
} 

Answer 1

它看起來對我來說，他們忘了其實附上RetainFragment不知何故到Activity等FragmentManager有機會找到它。未連接的碎片無法在配置更改後存活。

不知道，但它應與下面除了

public static RetainFragment findOrCreateRetainFragment(FragmentManager fm) { 
    RetainFragment fragment = (RetainFragment) fm.findFragmentByTag(TAG); 
    if (fragment == null) { 
     fragment = new RetainFragment(); 
     // add this line 
     fm.beginTransaction().add(fragment, TAG).commit(); 
    } 
    return fragment; 
}