0
我有一個問題，只出現幾個小時的不活動後，我研究了它的嘗試各種方式來修復它無濟於事。這個問題是在我的應用程序休眠了好幾個小時後，我的碎片引用爲空，但是;他們仍然存在於碎片管理器中。我使用引用來拉標籤，或者通過findfragmentby ...（）獲得id，這樣我就可以調用它們中的特定方法來更新自己，而不是更新它們。這些片段是動態的，並有一個用戶界面。我有幾項活動和一項主要活動要求的服務。我可以關閉應用程序並恢復，調用活動，從服務中提取信息，關閉，使用後退按鈕，全部沒有問題。爲了讓您的應用程序是如何構成的一個想法......片段參考null在簡歷
public class appClass extends Application {
public Fragment fragmentA;
public Fragment fragmentB;
public Fragment fragmentC;
@Override
public void onCreate() {
super.onCreate();
new fragmentTemplate();
fragemntA = fragmentTemplate.newInstance(getDbName(), usefuldata, "A List");
new fragmentTemplate();
fragemntB = fragmentTemplate.newInstance(getDbName(), usefuldata, "B list");
new fragmentTemplate();
fragemntC = fragmentTemplate.newInstance(getDbName(), usefuldata, "C list");
}
}
移動到哪裏片段以viewager使用活動...
public class mainActivity extends AppCompatActivity implements ...listeners{
appClass myAppClass;
FragmentManager FragMgr;
ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
myAppClass = (appClass) getApplication();
setTheme(myAppClass.getAppTheme());
setContentView(R.layout.activity_my_layout);
//toolbar actionbar stuff
FragMgr = getSupportFragmentManager();
viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new ViewPagerAdapter(FragMgr));
//tab setup
}
//inner class pager adapter is here
}
這是我的傳呼機適配器
class ViewPagerAdapter extends FragmentPagerAdapter implements ViewPager.OnPageChangeListener{
Fragment fragment;
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
if (myAppClass.fragmentA != null) {
fragment = myAppClass.fragemntA ;
}
break;
case 1:
if (myAppClass.fragmentB != null) {
fragment = myAppClass.fragmentB ;
}
break;
case 2:
if (myAppClass.fragmentC != null) {
fragment = myAppClass.fragmentC ;
}
break;
}
return fragment;
}
@Override
public int getCount() {
return 3;
}
}
我有一個FAB和聽衆看起來像這樣
@Override
public void onClick(View v) {
Fraggment fragment;
int i = viewPager.getCurrentItem();
if (v.getId() == floatingActionButton.getId()) {
switch (i) {
case 0:
fragment= (Fragment) FragMgr.findFragmentByTag(myAppClass.fragmentA.getTag());
fragment.addItem(fragment.getSomeString());
break;
case 1:
fragment= (Fragment) FragMgr.findFragmentByTag(myAppClass.fragmentB.getTag());
fragment.addItem(fragment.getSomeString());
break;
case 2:
fragment= (Fragment) FragMgr.findFragmentByTag(myAppClass.fragmentC.getTag());
fragment.addItem(fragment.getSomeString());
break;
}
}
}
代碼片段
public class fragmentTemplate extends Fragment implements RecyclerAdapter.aListener {
private appClass myAppclassReference;
private RecyclerView recyclerView;
private View view;
private FragmentTitle;
public static fragmentTemplate newInstance(String a, String b, String c) {
Bundle args = new Bundle();
args.putString(KEY_A, a);
args.putString(KEY_B, b);
args.putString(KEY_C, c);
fragmentTemplate fragment = new fragmentTemplate();
fragment.setArguments(args);
return fragment;
}
public String getFragmentTitle() {
return fragmentTitle;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, final Bundle savedInstanceState) {
view = inflater.inflate(R.layout.list, container, false);
myAppclassReference= ((appClass) getActivity().getApplication());
recyclerView = (RecyclerView) view.findViewById(R.id.listView);
//get list is a local function that loads a list from a db source
RecyclerAdapter recycler = new RecyclerAdapter(getActivity(), getList());
recycler.setListener(this);
recyclerView.setAdapter(recycler);
recyclerView.setLayoutManager(newLearLayoutManager(getActivity()));
recyclerView.addOnItemTouchListener(new RecyclerTouchListener(getActivity(), recyclerView, new ClickListener() {}};
return view;
}
}
當事情靠不住的應用程序不會崩潰馬上，標籤依然滾動時，viewpager仍然滾動，但它是空的，它不是直到我打了FAB做我得到一個nullpointerexception，試圖在onClick Listener中的一個空指針引用上調用一個方法，它實際上是否會崩潰。