我在视图分页器中有四个选项卡我在Google中进行了搜索，但是在滑动视图分页器时像1-2-3-4一样可以正常工作，但是当我尝试向后滑动4-3-2时却找不到任何解决方案-1比我的数据丢失或可以说我的适配器丢失。我的View Pager位于Activity内。当我转到下一页然后返回时，我的数据丢失了。
我的主要活动是：
public class MainActivity extends AppCompatActivity {
public static int notificationCountCart = 0;
Toolbar toolbar;
ActionBar actionBar;
static ViewPager viewPager;
static TabLayout tabLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
if (toolbar != null)
setSupportActionBar(toolbar);
actionBar = getSupportActionBar();
if (actionBar != null) {
TextView textView = new TextView(this);
textView.setText("Shopping");
textView.setTextSize(20);
textView.setTypeface(null, Typeface.BOLD);
textView.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
textView.setGravity(Gravity.CENTER);
textView.setTextColor(getResources().getColor(R.color.white));
getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getSupportActionBar().setCustomView(textView);
actionBar.setDisplayShowTitleEnabled(false);
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setHomeAsUpIndicator(new IconDrawable(this, FontAwesomeIcons.fa_angle_left).colorRes(R.color.white).actionBarSize());
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
viewPager = (ViewPager) findViewById(R.id.viewpagerrr);
tabLayout = (TabLayout) findViewById(R.id.tabs);
setupViewPager(viewPager);
tabLayout.setupWithViewPager(viewPager);
}
@Override
protected void onResume() {
super.onResume();
invalidateOptionsMenu();
}
@Override
public void onBackPressed() {
super.onBackPressed();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
// Get the notifications MenuItem and
// its LayerDrawable (layer-list)
MenuItem item = menu.findItem(R.id.action_cart);
NotificationCountSetClass.setAddToCart(MainActivity.this, item, notificationCountCart);
// force the ActionBar to relayout its MenuItems.
// onCreateOptionsMenu(Menu) will be called again.
invalidateOptionsMenu();
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_search) {
startActivity(new Intent(MainActivity.this, SearchResultActivity.class));
return true;
} else if (id == R.id.action_cart) {
/* NotificationCountSetClass.setAddToCart(MainActivity.this, item, notificationCount);
invalidateOptionsMenu();*/
startActivity(new Intent(MainActivity.this, CartListActivity.class));
/* notificationCount=0;//clear notification count
invalidateOptionsMenu();*/
return true;
} else if (id == android.R.id.home) {
Intent intent = new Intent(MainActivity.this, HomeActivity.class);
startActivity(intent);
// startActivity(new Intent(MainActivity.this, EmptyActivity.class));
}
return super.onOptionsItemSelected(item);
}
private void setupViewPager(ViewPager viewPager) {
Adapter adapter = new Adapter(getSupportFragmentManager());
ImageListFragment fragment = new ImageListFragment();
SpeakerFragment speakerFragment = new SpeakerFragment();
adapter.addFragment(fragment, getString(R.string.item_2));
adapter.addFragment(speakerFragment, getString(R.string.item_4));
adapter.addFragment(new HeadPhone(), getString(R.string.item_3));
adapter.addFragment(new Offer(), getString(R.string.item_1));
viewPager.setAdapter(adapter);
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
static class Adapter extends FragmentPagerAdapter {
private final List<Fragment> mFragments = new ArrayList<>();
private final List<String> mFragmentTitles = new ArrayList<>();
public Adapter(FragmentManager fm) {
super(fm);
}
public void addFragment(Fragment fragment, String title) {
mFragments.add(fragment);
mFragmentTitles.add(title);
}
@Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
@Override
public int getCount() {
return mFragments.size();
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitles.get(position);
}
}
}
我的片段是
public class ImageListFragment extends Fragment {
String category_Name, Category_ID, Product_ID, Product_Name,
Product_Image, Product_Price, Product_Sale, Cart;
public static final String STRING_IMAGE_URI = "ImageUri";
public static final String STRING_IMAGE_POSITION = "ImagePosition";
private static MainActivity mActivity;
ArrayList<SingleItemModel> singleItemModels;
RecyclerView recyclerView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getCategoryone();
Fresco.initialize(getContext());
mActivity = (MainActivity) getActivity();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
recyclerView = (RecyclerView) inflater.inflate(R.layout.layout_recylerview_list, container, false);
return recyclerView;
}
public static class SimpleStringRecyclerViewAdapter
extends RecyclerView.Adapter<ImageListFragment.SimpleStringRecyclerViewAdapter.ViewHolder> {
// private String[] mValues;
private ArrayList<SingleItemModel> mValues;
private RecyclerView mRecyclerView;
public static class ViewHolder extends RecyclerView.ViewHolder {
public final View mView;
public final SimpleDraweeView mImageView;
public final LinearLayout mLayoutItem;
public final ImageView mImageViewWishlist;
TextView iTemName, itemDescription, itemPrice;
public ViewHolder(View view) {
super(view);
mView = view;
mImageView = (SimpleDraweeView) view.findViewById(R.id.image1);
mLayoutItem = (LinearLayout) view.findViewById(R.id.layout_item);
mImageViewWishlist = (ImageView) view.findViewById(R.id.ic_wishlist);
iTemName = (TextView) view.findViewById(R.id.itemName);
itemDescription = (TextView) view.findViewById(R.id.itemDescription);
itemPrice = (TextView) view.findViewById(R.id.itemPrice);
}
}
public SimpleStringRecyclerViewAdapter(RecyclerView recyclerView, ArrayList<SingleItemModel> items) {
mValues = items;
mRecyclerView = recyclerView;
}
@Override
public ImageListFragment.SimpleStringRecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, parent, false);
return new ImageListFragment.SimpleStringRecyclerViewAdapter.ViewHolder(view);
}
@Override
public void onViewRecycled(ImageListFragment.SimpleStringRecyclerViewAdapter.ViewHolder holder) {
if (holder.mImageView.getController() != null) {
holder.mImageView.getController().onDetach();
}
if (holder.mImageView.getTopLevelDrawable() != null) {
holder.mImageView.getTopLevelDrawable().setCallback(null);
//
}
}
@Override
public void onBindViewHolder(final ImageListFragment.SimpleStringRecyclerViewAdapter.ViewHolder holder, final int position) {
SingleItemModel singleItemModel = mValues.get(position);
holder.iTemName.setText(singleItemModel.getCategory_Name());
final Uri uri = Uri.parse(singleItemModel.getProduct_Image());
holder.mImageView.setImageURI(uri);
holder.itemPrice.setText(singleItemModel.getProduct_Price());
holder.itemDescription.setText(singleItemModel.getProduct_Sale());
}
@Override
public int getItemCount() {
return mValues.size();
}
}
public void getCategoryone() {
final RequestQueue queue = Volley.newRequestQueue(getActivity());
StringRequest stringRequest = new StringRequest(Request.Method.POST, "http://proaudiobrands.com/app/feature.php",
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Log.i("shabina shopping response", response);
try {
singleItemModels = new ArrayList<>();
JSONObject mainObj = new JSONObject(response);
Log.d("shabina ", response);
JSONArray Feature_product = mainObj.getJSONArray("Feature_product");
for (int i = 0; i < Feature_product.length(); i++) {
JSONObject Feature_Product = Feature_product.getJSONObject(i);
String Category_Namee = Feature_Product.getString("Category_Namee");
String Category_IDs = Feature_Product.getString("Category_IDs");
JSONArray Product_List = Feature_Product.getJSONArray("Product_List");
for (int j = 0; j < Product_List.length(); j++) {
JSONObject Category_Name = Product_List.getJSONObject(j);
if (Category_Name.getString("Category_Name").equals("Microphones")) {
category_Name = Category_Name.getString("Category_Name");
Category_ID = Category_Name.getString("Category_ID");
Product_ID = Category_Name.getString("Product_ID");
Product_Name = Category_Name.getString("Product_Name");
Product_Image = Category_Name.getString("Product_Image");
Product_Price = Category_Name.getString("Product_Price");
Product_Sale = Category_Name.getString("Product_Sale");
Cart = Category_Name.getString("Cart");
Log.e("sushil Category_Name", category_Name + " " + Category_ID + " " + Product_ID + " " + Product_Name + " " + Product_Image + " " + Product_Price + " " + Product_Sale + " " + Cart);
SingleItemModel singleItemModel1 = new SingleItemModel(category_Name, Category_ID, Product_ID, Product_Name, Product_Image, Product_Price, Product_Sale, Cart);
singleItemModels.add(singleItemModel1);
}
StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(new ImageListFragment.SimpleStringRecyclerViewAdapter(recyclerView, singleItemModels));
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e("error", error.toString());
}
}) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> params = new HashMap<>();
params.put("method", "feature");
params.put("userId", "PRO1");
return params;
}
};
stringRequest.setRetryPolicy(new DefaultRetryPolicy(
90000,
DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
queue.add(stringRequest);
}
}
最佳答案
将您的MainActivity替换为以下内容
public class MainActivity extends AppCompatActivity {
public static int notificationCountCart = 0;
Toolbar toolbar;
ActionBar actionBar;
static ViewPager viewPager;
static TabLayout tabLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
if (toolbar != null)
setSupportActionBar(toolbar);
actionBar = getSupportActionBar();
if (actionBar != null) {
TextView textView = new TextView(this);
textView.setText("Shopping");
textView.setTextSize(20);
textView.setTypeface(null, Typeface.BOLD);
textView.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
textView.setGravity(Gravity.CENTER);
textView.setTextColor(getResources().getColor(R.color.white));
getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getSupportActionBar().setCustomView(textView);
actionBar.setDisplayShowTitleEnabled(false);
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setHomeAsUpIndicator(new IconDrawable(this, FontAwesomeIcons.fa_angle_left).colorRes(R.color.white).actionBarSize());
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
viewPager = (ViewPager) findViewById(R.id.viewpagerrr);
viewPager.setOffscreenPageLimit(4);
tabLayout = (TabLayout) findViewById(R.id.tabs);
setupViewPager(viewPager);
tabLayout.setupWithViewPager(viewPager);
}
@Override
protected void onResume() {
super.onResume();
invalidateOptionsMenu();
}
@Override
public void onBackPressed() {
super.onBackPressed();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
// Get the notifications MenuItem and
// its LayerDrawable (layer-list)
MenuItem item = menu.findItem(R.id.action_cart);
NotificationCountSetClass.setAddToCart(MainActivity.this, item, notificationCountCart);
// force the ActionBar to relayout its MenuItems.
// onCreateOptionsMenu(Menu) will be called again.
invalidateOptionsMenu();
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_search) {
startActivity(new Intent(MainActivity.this, SearchResultActivity.class));
return true;
} else if (id == R.id.action_cart) {
/* NotificationCountSetClass.setAddToCart(MainActivity.this, item, notificationCount);
invalidateOptionsMenu();*/
startActivity(new Intent(MainActivity.this, CartListActivity.class));
/* notificationCount=0;//clear notification count
invalidateOptionsMenu();*/
return true;
} else if (id == android.R.id.home) {
Intent intent = new Intent(MainActivity.this, HomeActivity.class);
startActivity(intent);
// startActivity(new Intent(MainActivity.this, EmptyActivity.class));
}
return super.onOptionsItemSelected(item);
}
private void setupViewPager(ViewPager viewPager) {
Adapter adapter = new Adapter(getSupportFragmentManager());
ImageListFragment fragment = new ImageListFragment();
SpeakerFragment speakerFragment = new SpeakerFragment();
adapter.addFragment(fragment, getString(R.string.item_2));
adapter.addFragment(speakerFragment, getString(R.string.item_4));
adapter.addFragment(new HeadPhone(), getString(R.string.item_3));
adapter.addFragment(new Offer(), getString(R.string.item_1));
viewPager.setAdapter(adapter);
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
static class Adapter extends FragmentPagerAdapter {
private final List<Fragment> mFragments = new ArrayList<>();
private final List<String> mFragmentTitles = new ArrayList<>();
public Adapter(FragmentManager fm) {
super(fm);
}
public void addFragment(Fragment fragment, String title) {
mFragments.add(fragment);
mFragmentTitles.add(title);
}
@Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
@Override
public int getCount() {
return mFragments.size();
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitles.get(position);
}
}
}
关于java - 当我从下一个选项卡返回时，我丢失了查看寻呼机数据，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/47990149/