切換回SupportMapFragment顯示一個空白活動

我有一個SuportMap片段的問題，當它切換回地圖片段時顯示一個空白片段，這種情況是：我有左側抽屜的主要活動，該抽屜包含兩個項目以顯示片段A和片段B，片段A包含具有2個選項卡（地圖選項卡和第二選項卡）的選項卡主機。應用程序在午餐時顯示地圖，但沒關係，但如果我選擇抽屜中的第二個項目轉到片段B並返回片段A，則Map片段顯示一個空白片段，如果我選擇另一個選項卡並返回到地圖選項卡，然後再次成功顯示地圖。我不知道什麼是錯的。切換回SupportMapFragment顯示一個空白活動

MainActivity：

public boolean onNavigationItemSelected(@NonNull MenuItem item) { 
// Handle navigation view item clicks here. 
int id = item.getItemId(); 

MainFragment mainFragment = (MainFragment) getSupportFragmentManager().findFragmentByTag(MainFragment.TAG); 

if (id == R.id.nav_home && mainFragment == null) { 
    showFragment(new MapFragment(), "MapFragment"); 
} else if (id == R.id.nav_gallery && 
     getSupportFragmentManager().findFragmentByTag(GalleryFragment.TAG) == null) { 
    showFragment(new B(), "B"); 
} 

DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
assert drawer != null; 
drawer.closeDrawer(GravityCompat.START); 
return true; 
} 

public void showFragment(Fragment fragment, String tag) { 
     FragmentManager manager = getSupportFragmentManager(); 
     boolean fragmentPopped = manager.popBackStackImmediate(tag, 0); 

    if (!fragmentPopped) { //fragment not in back stack, create it. 
     FragmentTransaction ft = manager.beginTransaction(); 
     ft.replace(R.id.content, fragment); 
     ft.addToBackStack(tag); 
     ft.commit(); 
    } 
}

片段A：

private void initTabHost() { 
    mTHost.setOnTabChangedListener(this); 
    mTHost.setup(); 

    TabHost.TabSpec MapSpec = mTHost.newTabSpec(PeopleFragment.TAG); 
    MapSpec.setIndicator(getTabIndicator(R.string.tool_bar_people, R.drawable.selector_map_tab)); 
    MapSpec.setContent(new DummyTabContent(getActivity())); 
    mTHost.addTab(MapSpec); 

    TabHost.TabSpec secondSpec = mTHost.newTabSpec(SecondFragment.TAG); 
    secondSpec.setIndicator(getTabIndicator(R.string.tool_bar_news, R.drawable.selector_second_tab)); 
    secondSpec.setContent(new DummyTabContent(getActivity())); 
    mTHost.addTab(secondSpec); 
} 

private View getTabIndicator(int title, int icon) { 
    View view = LayoutInflater.from(getActivity()).inflate(R.layout.item_tab_layout, null); 

    ImageView ivIcon = (ImageView) view.findViewById(R.id.iv_icon); 
    ivIcon.setImageResource(icon); 

    TextView tvTitle = (TextView) view.findViewById(R.id.tv_title); 
    tvTitle.setText(title); 

    return view; 
} 

@Override 
public void onTabChanged(String tabId) { 
    FragmentManager fragmentManager = getActivity().getSupportFragmentManager(); 
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); 

    MapFragment mapFragment = (MapFragment) fragmentManager.findFragmentByTag(MapFragment.TAG); 
    SecondFragment secondFragment = (SecondFragment) fragmentManager.findFragmentByTag(SecondFragment.TAG); 

    if (mapFragment != null) { 
     fragmentTransaction.detach(mapFragment); 
    } 
    if (secondFragment != null) { 
     fragmentTransaction.detach(secondFragment); 
    } 

    if (tabId.equalsIgnoreCase(MapFragment.TAG)) { 
     if (mapFragment == null) { 
      fragmentTransaction.add(R.id.fl_real_tab_content, new MapFragment(), MapFragment.TAG); 
     } else { 
      fragmentTransaction.attach(mapFragment); 
     } 
    } else if (tabId.equalsIgnoreCase(SecondFragment.TAG)) { 
     if (secondFragment == null) { 
      fragmentTransaction.add(R.id.fl_real_tab_content, new SecondFragment(), SecondFragment.TAG); 
     } else { 
      fragmentTransaction.attach(SecondFragment); 
     } 
    } 
    fragmentTransaction.commit(); 
}

MapFragment：

@Override 
public void onResume() { 
    super.onResume(); 
    setUpMapIfNeeded(); 
} 
public void setUpMapIfNeeded() { 
    // Do a null check to confirm that we have not already instantiated the mMap. 
    ((SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map)) 
      .getMapAsync(this); 
}

任何幫助我該做什麼以及有什麼問題？

來源

2016-12-28 Amjad Omari

你檢查了日誌嗎？一定有一些東西在裏面。 –

是的，我檢查了日誌，並沒有任何錯誤，我已經跟蹤它。但它似乎是附加和分離地圖片段的問題。 –

我已經在解決方案中解決了此問題，通過將android:launchMode=="SingleInstance"添加到清單文件中的活動中。在這種情況下，當我們回到活動時，活動將不會創建新的片段並從頭開始重置狀態。

來源

2017-04-29 00:12:56

切換回SupportMapFragment顯示一個空白活動

回答

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