如何在android中使用底部导航视图时恢复片段状态？
Posted
技术标签:
【中文标题】如何在android中使用底部导航视图时恢复片段状态？【英文标题】：How to restore fragment states while using bottom navigation view in android? 【发布时间】：2019-12-02 14:51:55 【问题描述】：我正在尝试从 android 底部导航视图中的第二个片段返回时恢复片段视图状态值（文本视图，..etc）。
MyActivity.java
public class LandingPage extends AppCompatActivity implements ProductFragment.AddToCart
Fragment fragment;
TextView txtCart;
Button btnCart;
ItemData itemData;
ArrayList<ItemData> itemDataList;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener = new BottomNavigationView.OnNavigationItemSelectedListener()
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item)
switch (item.getItemId())
case R.id.nav_home:
fragment = new ProductFragment();
loadFragment(fragment);
return true;
case R.id.nav_profile:
fragment = new ReportsFragment();
loadFragment(fragment);
return true;
case R.id.nav_logout:
LogOut();
return true;
return true;
;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_landing_page);
txtCart = findViewById(R.id.txt_cart);
btnCart = findViewById(R.id.btn_cartImg);
itemDataList = new ArrayList<>();
BottomNavigationView bottomNavigationView = findViewById(R.id.navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
loadFragment(new ProductFragment());
private void loadFragment(Fragment fragment)
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_container, fragment);
transaction.commit();
ProductFragment.java
public class ProductFragment extends Fragment
private OnFragmentInteractionListener mListener;
Button btnCart1,btnCart2,btnCart3;
AddToCart addToCart;
TextView txtItem1Des,txtItem1Price,txtItem2Des,txtItem2Price,txtItem3Des,txtItem3Price;
Button btnCart1Inc,btnCart1Dec,btnCart2Inc,btnCart2Dec,btnCart3Inc,btnCart3Dec;
TextView cart1txt,cart2txt,cart3txt;
String itemDes,itemPrice,itemImg,itemCount;
int quantity1,quantity2,quantity3;
public ProductFragment()
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_product, container, false);
btnCart1 = view.findViewById(R.id.cart1);
txtItem1Des = view.findViewById(R.id.cart1_desc);
txtItem1Price = view.findViewById(R.id.cart1_price);
btnCart1Inc = view.findViewById(R.id.cart1Inc);
btnCart1Dec = view.findViewById(R.id.cart1Dec);
cart1txt = view.findViewById(R.id.cart1txt);
btnCart2 = view.findViewById(R.id.cart2);
txtItem2Des = view.findViewById(R.id.cart2_desc);
txtItem2Price = view.findViewById(R.id.cart2_price);
btnCart2Inc = view.findViewById(R.id.cart2Inc);
btnCart2Dec = view.findViewById(R.id.cart2Dec);
cart2txt = view.findViewById(R.id.cart2txt);
btnCart3 = view.findViewById(R.id.cart3);
txtItem3Des = view.findViewById(R.id.cart3_desc);
txtItem3Price = view.findViewById(R.id.cart3_price);
btnCart3Inc = view.findViewById(R.id.cart3Inc);
btnCart3Dec = view.findViewById(R.id.cart3Dec);
cart3txt = view.findViewById(R.id.cart3txt);
quantity1 = Integer.parseInt(cart1txt.getText().toString());
quantity2 = Integer.parseInt(cart2txt.getText().toString());
quantity3 = Integer.parseInt(cart3txt.getText().toString());
buttonInitialization();
addingToCart();
return view;
private void addingToCart()
btnCart1Dec.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
if(quantity1 <= 1)
btnCart1.setVisibility(View.VISIBLE);
btnCart1Dec.setVisibility(View.INVISIBLE);
btnCart1Inc.setVisibility(View.INVISIBLE);
cart1txt.setVisibility(View.INVISIBLE);
addToCart.removeItemFromCart(1);
else
quantity1 = quantity1-1;
cart1txt.setText(String.valueOf(quantity1));
addToCart.itemCount(cart1txt.getText().toString(),"1");
);
btnCart1Inc.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
quantity1 = quantity1+1;
cart1txt.setText(String.valueOf(quantity1));
addToCart.itemCount(cart1txt.getText().toString(),"1");
);
btnCart2Dec.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
if(quantity2 <= 1)
btnCart2.setVisibility(View.VISIBLE);
btnCart2Dec.setVisibility(View.INVISIBLE);
btnCart2Inc.setVisibility(View.INVISIBLE);
cart2txt.setVisibility(View.INVISIBLE);
addToCart.removeItemFromCart(2);
else
quantity2 = quantity2-1;
cart2txt.setText(String.valueOf(quantity2));
addToCart.itemCount(cart2txt.getText().toString(),"2");
);
btnCart2Inc.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
quantity2 = quantity2+1;
cart2txt.setText(String.valueOf(quantity2));
addToCart.itemCount(cart2txt.getText().toString(),"2");
);
btnCart3Dec.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
if(quantity3 <= 1)
btnCart3.setVisibility(View.VISIBLE);
btnCart3Dec.setVisibility(View.INVISIBLE);
btnCart3Inc.setVisibility(View.INVISIBLE);
cart3txt.setVisibility(View.INVISIBLE);
addToCart.removeItemFromCart(3);
else
quantity3 = quantity3-1;
cart3txt.setText(String.valueOf(quantity3));
addToCart.itemCount(cart3txt.getText().toString(),"3");
);
btnCart3Inc.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
quantity3 = quantity3+1;
cart3txt.setText(String.valueOf(quantity3));
addToCart.itemCount(cart3txt.getText().toString(),"3");
);
private void buttonInitialization()
btnCart1.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
itemImg = "";
itemPrice = txtItem1Price.getText().toString().trim();
itemDes = txtItem1Des.getText().toString().trim();
itemCount = cart1txt.getText().toString().trim();
addToCart.cartCount("",itemPrice,itemDes,itemCount,"1");
btnCart1.setVisibility(View.INVISIBLE);
btnCart1Dec.setVisibility(View.VISIBLE);
btnCart1Inc.setVisibility(View.VISIBLE);
cart1txt.setVisibility(View.VISIBLE);
);
btnCart2.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
itemImg = "";
itemPrice = txtItem2Price.getText().toString().trim();
itemDes = txtItem2Des.getText().toString().trim();
itemCount = cart2txt.getText().toString().trim();
addToCart.cartCount("",itemPrice,itemDes,itemCount,"2");
btnCart2.setVisibility(View.INVISIBLE);
btnCart2Dec.setVisibility(View.VISIBLE);
btnCart2Inc.setVisibility(View.VISIBLE);
cart2txt.setVisibility(View.VISIBLE);
);
btnCart3.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
itemImg = "";
itemPrice = txtItem3Price.getText().toString().trim();
itemDes = txtItem3Des.getText().toString().trim();
itemCount = cart3txt.getText().toString().trim();
addToCart.cartCount("",itemPrice,itemDes,itemCount,"3");
btnCart3.setVisibility(View.INVISIBLE);
btnCart3Dec.setVisibility(View.VISIBLE);
btnCart3Inc.setVisibility(View.VISIBLE);
cart3txt.setVisibility(View.VISIBLE);
);
public void onButtonPressed(Uri uri)
if (mListener != null)
mListener.onFragmentInteraction(uri);
@Override
public void onAttach(Context context)
super.onAttach(context);
addToCart = (AddToCart) context;
@Override
public void onDetach()
super.onDetach();
mListener = null;
public interface OnFragmentInteractionListener
void onFragmentInteraction(Uri uri);
public interface AddToCart
void cartCount(String item_img,String item_price,String item_desc,String item_count,String item_pos);
void removeItemFromCart(int removeItem);
void itemCount(String itemCount,String position);
在 ProductFragment 中，我将向文本视图添加值。当我来自 ReportFragment 时，视图值将在 ProductFragment 中被清除。
【问题讨论】：
不是替换片段，而是添加它。它会覆盖当前的。 ReportFragments 包含不同的视图。如果我们添加片段。 ProductFragment 视图将出现在 ReportFragment 中。 @amarlucky 将片段添加到堆栈，同时替换并在后按时弹出 【参考方案1】：我会考虑分两步进行：
保存片段实例而不是每次都重新创建一个新实例
private ProductFragment productFragment;
private ReportsFragment reportsFragment;
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener = new BottomNavigationView.OnNavigationItemSelectedListener()
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item)
switch (item.getItemId())
case R.id.nav_home:
if(productFragment == null)
productFragment = new ProductFragment();
loadFragment(productFragment);
break;
case R.id.nav_profile:
if(reportsFragment == null)
reportsFragment = new ReportsFragment();
loadFragment(reportsFragment);
break;
case R.id.nav_logout:
LogOut();
return true;
return true;
;
参考this question/answer，您应该在片段中同时实现void onSaveInstanceState(final Bundle outState) 和void onActivityCreated(Bundle savedInstanceState)
这样，您肯定会保留片段的实例，而不是每次都创建一个新实例（new MyFragment() 将始终重新创建它）。此外，将您的视图状态保存在 onSaveInstanceState 并将其恢复到您的 onActivityCreate，将允许您保留您的视图/值。
我是在没有编译器的情况下手工编写的，所以它可能并不完美。
如果您需要更多信息，请告诉我。
祝你好运
【讨论】：
我试过它对我不起作用。我刚刚使用了这个解决方案 medium.com/@oluwabukunmi.aluko/… ，它对我有用。【参考方案2】：我正在使用this solution，它对我有用。
【讨论】：
感谢@faranjit，您的解决方案对我有用。我从一天开始尝试。现在它工作正常。【参考方案3】：您应该看到my detailed answer 来回答类似的问题。希望能解决你的问题。
【讨论】：
以上是关于如何在android中使用底部导航视图时恢复片段状态？的主要内容，如果未能解决你的问题，请参考以下文章
Android - 恢复 Fragment WebView 状态以避免重新加载