Question

我从api链接（服务器）获取数据以显示recyclview中的数据，如果我想点击项目然后它会打开下一个活动很好，但有些项目没有数据，如果我想点击geting类强制转换异常

在上面的图片中，点击冒险，然后它将打开下一个活动及相关数据，如果我想点击儿童活动然后获得类别转换异常错误，因为从服务器没有数据可用于儿童活动，如果我想点击儿童活动，那么它将打开吐司按摩，因为没有更多的数据可用，我应该如何得到它？

这是适配器类

winrm

这是模型类

public class SubCategoryChild_Adapter extends RecyclerView.Adapter {

private List<SubCategoryChild> subCategoryChildList;
private Context context;

public class MyViewHolder extends RecyclerView.ViewHolder {
    public TextView
            discountName,
            subcategorychild_merchantName,
            subcategoryChild_discountedPrice,
            subcategoryChild_actualPrice,
            subcategoryChild_distance,
            staticUgx;
    public ImageView SubcategoryChild_imageView;
    public SubCategoryChild subCategoryChild;

    public MyViewHolder(View view) {
        super(view);
        subcategoryChild_actualPrice = (TextView) view.findViewById(R.id.ScChild_actualPrice);
        subcategoryChild_actualPrice.setPaintFlags(subcategoryChild_actualPrice.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);

        subcategoryChild_discountedPrice = (TextView) view.findViewById(R.id.ScChild_discountedPrice);
        subcategorychild_merchantName = (TextView) view.findViewById(R.id.ScChild_merchantName);

        staticUgx = (TextView) view.findViewById(R.id.ScChild_actualprice_ugx);
        staticUgx.setPaintFlags(staticUgx.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);

        subcategoryChild_distance = (TextView) view.findViewById(R.id.ScChild_Near_Location_text);

        discountName = (TextView) view.findViewById(R.id.ScChild_Discount_Text);
        SubcategoryChild_imageView = (ImageView) view.findViewById(R.id.ScChild_imageView);
    }
}

public SubCategoryChild_Adapter(Context context , List<SubCategoryChild> subCategoryChildList) {
    this.subCategoryChildList = subCategoryChildList;
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    RecyclerView.ViewHolder itemView;
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.subcategorydeal_list, parent, false);
    itemView = new MyViewHolder(view);
    return itemView;
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder,int position){
    final SubCategoryChild subCategoryChild = subCategoryChildList.get(position);
    ((MyViewHolder) holder).subcategorychild_merchantName.setText(subCategoryChild.getMerchantName());
    ((MyViewHolder) holder).discountName.setText(subCategoryChild.getName());
    ((MyViewHolder) holder).subcategoryChild_actualPrice.setText(subCategoryChild.getActualPrice());
    ((MyViewHolder) holder).subcategoryChild_discountedPrice.setText(subCategoryChild.getDiscountedPrice());
    ((MyViewHolder) holder).subcategoryChild_distance.setText(subCategoryChild.getDistance());

    context = ((MyViewHolder) holder).SubcategoryChild_imageView.getContext();

    Picasso.with(context).load(subCategoryChild.getLogo()).fit().into(((MyViewHolder)holder).SubcategoryChild_imageView);
    ((MyViewHolder) holder).subCategoryChild = subCategoryChild;
}
@Override
public int getItemCount() {
    if(subCategoryChildList == null){
        return 0;
    }else {
        return subCategoryChildList.size();
    }

}
}

这是活动类

public class SubCategoryChild {

@SerializedName("merchant_id")
@Expose
private String merchantId;
@SerializedName("merchant_name")
@Expose
private String merchantName;
@SerializedName("name")
@Expose
private String name;
@SerializedName("deal_sub_title")
@Expose
private String dealSubTitle;
@SerializedName("discounted_price")
@Expose
private String discountedPrice;
@SerializedName("actual_price")
@Expose
private String actualPrice;
@SerializedName("discounted_percentage")
@Expose
private String discountedPercentage;
@SerializedName("category_id")
@Expose
private String categoryId;
@SerializedName("sub_category_id")
@Expose
private String subCategoryId;
@SerializedName("city_id")
@Expose
private String cityId;
@SerializedName("logo")
@Expose
private String logo;
@SerializedName("website")
@Expose
private String website;
@SerializedName("email")
@Expose
private String email;
@SerializedName("phone")
@Expose
private String phone;
@SerializedName("mobile")
@Expose
private String mobile;
@SerializedName("description")
@Expose
private String description;
@SerializedName("Merchant_address")
@Expose
private String merchantAddress;
@SerializedName("latitude")
@Expose
private String latitude;
@SerializedName("longitude")
@Expose
private String longitude;
@SerializedName("distance")
@Expose
private String distance;
@SerializedName("deal_count")
@Expose
private Integer dealCount;

public String getMerchantId() {
    return merchantId;
}

public void setMerchantId(String merchantId) {
    this.merchantId = merchantId;
}

public String getMerchantName() {
    return merchantName;
}

public void setMerchantName(String merchantName) {
    this.merchantName = merchantName;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getDealSubTitle() {
    return dealSubTitle;
}

public void setDealSubTitle(String dealSubTitle) {
    this.dealSubTitle = dealSubTitle;
}

public String getDiscountedPrice() {
    return discountedPrice;
}

public void setDiscountedPrice(String discountedPrice) {
    this.discountedPrice = discountedPrice;
}

public String getActualPrice() {
    return actualPrice;
}

public void setActualPrice(String actualPrice) {
    this.actualPrice = actualPrice;
}

public String getDiscountedPercentage() {
    return discountedPercentage;
}

public void setDiscountedPercentage(String discountedPercentage) {
    this.discountedPercentage = discountedPercentage;
}

public String getCategoryId() {
    return categoryId;
}

public void setCategoryId(String categoryId) {
    this.categoryId = categoryId;
}

public String getSubCategoryId() {
    return subCategoryId;
}

public void setSubCategoryId(String subCategoryId) {
    this.subCategoryId = subCategoryId;
}

public String getCityId() {
    return cityId;
}

public void setCityId(String cityId) {
    this.cityId = cityId;
}

public String getLogo() {
    return logo;
}

public void setLogo(String logo) {
    this.logo = logo;
}

public String getWebsite() {
    return website;
}

public void setWebsite(String website) {
    this.website = website;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getPhone() {
    return phone;
}

public void setPhone(String phone) {
    this.phone = phone;
}

public String getMobile() {
    return mobile;
}

public void setMobile(String mobile) {
    this.mobile = mobile;
}

public String getDescription() {
    return description;
}

public void setDescription(String description) {
    this.description = description;
}

public String getMerchantAddress() {
    return merchantAddress;
}

public void setMerchantAddress(String merchantAddress) {
    this.merchantAddress = merchantAddress;
}

public String getLatitude() {
    return latitude;
}

public void setLatitude(String latitude) {
    this.latitude = latitude;
}

public String getLongitude() {
    return longitude;
}

public void setLongitude(String longitude) {
    this.longitude = longitude;
}

public String getDistance() {
    return distance;
}

public void setDistance(String distance) {
    this.distance = distance;
}

public Integer getDealCount() {
    return dealCount;
}

public void setDealCount(Integer dealCount) {
    this.dealCount = dealCount;
}
}

这是响应类

public class SubCategoryChild_Activity extends AppCompatActivity {
RecyclerView subCategoryDeal_RecyclerView;
public Context context;
ProgressBar progress_bar;
SubCategoryChild_Adapter subCategoryChild_adapter;
List<SubCategoryChild> subCategoryChildList;
SubCategoryChild subCategoryChild;
public String catId,subCatId,ActionBar_Name;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_sub_category_child_);

    Bundle extras = getIntent().getExtras();
    catId = extras.getString("cat_Id");
    subCatId = extras.getString("Sub_CatId");
    ActionBar_Name = extras.getString("actionBar_Name");

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setDefaultDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setTitle(ActionBar_Name);

    subCategoryDeal_RecyclerView = (RecyclerView) findViewById(R.id.subCategoryDeal_RecyclerView);
    final ProgressBar progress_bar = (ProgressBar) findViewById(R.id.ScChild_progress_bar);
    subCategoryDeal_RecyclerView.setLayoutManager(new LinearLayoutManager(this));

    subCategoryDeal_RecyclerView.setHasFixedSize(true);

    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);
    subCategoryDeal_RecyclerView.setLayoutManager(layoutManager);

    subCategoryDeal_RecyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));
    subCategoryDeal_RecyclerView.setItemAnimator(new DefaultItemAnimator());
    subCategoryChild_adapter = new SubCategoryChild_Adapter(context, subCategoryChildList);
    subCategoryDeal_RecyclerView.setAdapter(subCategoryChild_adapter);

    progress_bar.setVisibility(View.VISIBLE);
    if(new SubCategoryChild_Response().getStatus() == null){

        RestClient.get(this).diskCacheEnable(true).new NetworkTask<Void, SubCategoryChild_Response>(SubCategoryChild_Response.class, Http.GET) {

            @Override
            protected void onPostExecute(SubCategoryChild_Response subCategoryChild_response) {
                super.onPostExecute(subCategoryChild_response);
                progress_bar.setVisibility(View.GONE);
                if (subCategoryChild_response != null && subCategoryChild_response.getSubCategoryChild() != null & subCategoryChild_response.getSubCategoryChild().size() > 0) {
                    subCategoryChildList = subCategoryChild_response.getSubCategoryChild();
                    subCategoryChild_adapter = new SubCategoryChild_Adapter(SubCategoryChild_Activity.this, subCategoryChildList);
                    subCategoryDeal_RecyclerView.setAdapter(subCategoryChild_adapter);
                }
            }
        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, "https://api.bargaincry.com/apurl/deal/get_merchantBy_subcat/41187/" + catId + "/" + subCatId + "/latitude~longitude");

    }else {
        if(new SubCategoryChild_Response().getStatus().isEmpty())
        Toast.makeText(SubCategoryChild_Activity.this,"error",Toast.LENGTH_LONG).show();
                }

}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    MenuInflater menuInflater = getMenuInflater();
    menuInflater.inflate(R.menu.navigation_,menu);
    //getMenuInflater().inflate(R.menu.navigation_, menu);

    // Associate searchable configuration with the SearchView

    SearchManager searchManager = (SearchManager)getSystemService(Context.SEARCH_SERVICE);
    SearchView searchView = (SearchView) menu.findItem(R.id.action_search).getActionView();
    ComponentName cn = new ComponentName(this, SearchResultsActivity.class);
    searchView.setSearchableInfo(searchManager.getSearchableInfo(cn));
    //searchView.setSubmitButtonEnabled(true);
    //searchView.setOnQueryTextListener(MainActivity.this);
    searchView.setIconifiedByDefault(false);
    return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            // app icon in action bar clicked; goto parent activity.
            this.finish();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}
}

这是catLog here

致命例外：主程序：app.com.BargainCryApp，PID：28129
java.lang.ClassCastException：java.lang.String无法强制转换为 models.SubCategoryChild_Response at app.com.BargainCryApp.SubCategoryChild_Activity $ 1.onPostExecute（SubCategoryChild_Activity.java:69）在android.os.AsyncTask.finish（AsyncTask.java:665）at android.os.AsyncTask.-wrap1（AsyncTask.java）at android.os.AsyncTask $ InternalHandler.handleMessage（AsyncTask.java:682）在android.os.Handler.dispatchMessage（Handler.java:111）处 android.os.Looper.loop（Looper.java:207）at android.app.ActivityThread.main（ActivityThread.java:5769）at java.lang.reflect.Method.invoke（Native Method）at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:861）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:751）

Answer 1

对于如何避免ClassCastException的问题，答案是使用＆＃39; instanceof＆＃39; operator和instanceof返回true然后进一步执行您的操作。

if (subCategoryChild_response != null && 
   subCategoryChild_response.getSubCategoryChild() != null && 
   subCategoryChild_response.getSubCategoryChild() instanceof 'Your Child Class should be here'
   subCategoryChild_response.getSubCategoryChild().size() > 0)

希望这有助于你

Answer 2

在投射对象之前，请检查instanceOf

  if (holder instanceof MyViewHolder) {
    MyViewHolder mHolder = (MyViewHolder) holder;
    mHolder.subcategorychild_merchantName.setText(subCategoryChild.getMerchantName());
//..........
  }

如何避免ClassCast异常

2 个答案: