Question

我正在开发新闻应用程序，并且在运行代码时在片段类中实现了dagger 2

Logcats：

致命异常：主要流程：edgar.yodgorbek.sportnews，PID：8567 java.lang.ClassCastException：edgar.yodgorbek.sportnews.component.DaggerApplicationComponent无法转换为edgar.yodgorbek.sportnews.component.BBCSportFragmentComponent 在edgar.yodgorbek.sportnews.sportactivities.BBCSportFragment $ 1.onResponse（BBCSportFragment.java:72）在retrofit2.ExecutorCallAdapterFactory $ ExecutorCallbackCall $ 1 $ 1.run（ExecutorCallAdapterFactory.java:70）在android.os.Handler.handleCallback（Handler.java:873）在android.os.Handler.dispatchMessage（Handler.java:99）在android.os.Looper.loop（Looper.java:209）

在BBCSportFragment.java 类之下：

public class BBCSportFragment extends Fragment implements ArticleAdapter.ClickListener {

public List<Article> articleList = new ArrayList<>();
@ActivityContext
public Context activityContext;
@ApplicationContext
public Context mContext;
@BindView(R.id.recycler_view)
RecyclerView recyclerView;
BBCSportFragmentComponent bbcSportFragmentComponent;
BBCFragmentContextModule bbcFragmentContextModule;
private SportNews sportNews;
private ArticleAdapter articleAdapter;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_bbcsport, container, false);
    Activity activity = getActivity();
    ButterKnife.bind(this, view);
    SportInterface sportInterface = SportClient.getApiService();
    Call<SportNews> call = sportInterface.getArticles();
    call.enqueue(new Callback<SportNews>() {
        @Override
        public void onResponse(Call<SportNews> call, Response<SportNews> response) {
            sportNews = response.body();
            if (sportNews != null && sportNews.getArticles() != null) {
                articleList.addAll(sportNews.getArticles());
            }
            articleAdapter = new ArticleAdapter(articleList, sportNews);
            ApplicationComponent applicationComponent = MyApplication.get(Objects.requireNonNull(activity)).getApplicationComponent();
            bbcSportFragmentComponent = (BBCSportFragmentComponent) DaggerApplicationComponent.builder().contextModule(new ContextModule(getContext())).build();
            bbcSportFragmentComponent.injectBBCSportFragment(BBCSportFragment.this);
            RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext());
            recyclerView.setLayoutManager(layoutManager);
            recyclerView.setAdapter(articleAdapter);
        }

        @Override
        public void onFailure(Call<SportNews> call, Throwable t) {
            Log.e("Error", "error");
        }
    });


    return view;


}

}

ArticleAdapter.java 类以下：

public class ArticleAdapter extends RecyclerView.Adapter<ArticleAdapter.CustomViewHolder> {

public static final String urlKey = "urlKey";
public static final String imageKey = "imageKey";
public ArticleAdapter.ClickListener listener;
Context context;
private List<Article> articles = new ArrayList<>();


public ArticleAdapter(List<Article> articles, SportNews sportNews) {
    this.articles = articles;
    this.listener = listener;

}

public ArticleAdapter(ArticleAdapter.ClickListener clickListener) {
}

@NonNull
@Override
public CustomViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View itemView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.article_list, null);
    return new CustomViewHolder(itemView);
}

@Override
public void onBindViewHolder(@NonNull CustomViewHolder customViewHolder, int position) {
    Article article = articles.get(position);
    if(article!=null){
        customViewHolder.articleAuthor.setText(article.getAuthor());
        customViewHolder.articleTitle.setText(article.getTitle());
        Picasso.get().load(article.getUrlToImage()).into(customViewHolder.articleImage);}
    customViewHolder.itemView.setOnClickListener(v -> {
        Intent intent = new Intent(v.getContext(), DetailActivity.class);

        intent.putExtra("urlKey", article.getUrl());
        intent.putExtra("imageKey", article.getUrlToImage());

        v.getContext().startActivity(intent);
    });





}


@Override
public int getItemCount() {
    if (articles == null) return 0;
    return articles.size();
}

public interface ClickListener {
}

public class CustomViewHolder extends RecyclerView.ViewHolder {
    @BindView(R.id.articleAuthor)
    TextView articleAuthor;
    @BindView(R.id.articleTitle)
    TextView articleTitle;
    @BindView(R.id.articleImage)
    ImageView articleImage;


    public CustomViewHolder(View view) {
        super(view);
        ButterKnife.bind(this, view);


    }
}

}

MyApplication.java 类以下：

public class MyApplication extends Application {
ApplicationComponent applicationComponent;

public static MyApplication get(Activity activity) {
    return (MyApplication) activity.getApplication();
}

@Override
public void onCreate() {
    super.onCreate();

    applicationComponent = DaggerApplicationComponent.builder().contextModule(new ContextModule(this)).build();
    applicationComponent.injectApplication(this);

}

public ApplicationComponent getApplicationComponent() {
    return applicationComponent;
}
}

在清单文件下面：

<?xml version="1.0" encoding="UTF-8"?>

<manifest package="edgar.yodgorbek.sportnews" xmlns:tools="http://schemas.android.com/tools" xmlns:android="http://schemas.android.com/apk/res/android">

<uses-permission android:name="android.permission.INTERNET"/>


-<application android:name=".component.MyApplication" tools:replace="android:appComponentFactory" tools:ignore="GoogleAppIndexingWarning" android:theme="@style/AppTheme" android:supportsRtl="true" android:roundIcon="@mipmap/ic_launcher_round" android:label="@string/app_name" android:icon="@mipmap/ic_launcher" android:appComponentFactory="@string/app_name" android:allowBackup="true">


-<activity android:name=".MainActivity">


<intent-filter>

<action android:name="android.intent.action.MAIN"/>

<category android:name="android.intent.category.LAUNCHER"/>

Answer 1

关于Dagger设置，这一行似乎不正确：

// BBCSportFragment.onCreate > Callback.onResponse
(BBCSportFragmentComponent) DaggerApplicationComponent.builder().contextModule(new ContextModule(getContext())).build();

正确的设置不需要您强制转换.build()的结果。

如果BBCSportFragmentComponent使用组件依赖项（带有@Component(dependencies = ApplicationComponent.class)之类的注释），也许您的意思是：

bbcSportFragmentComponent =
    DaggerBBCSportFragmentComponent.builder()
        .applicationComponent(applicationComponent)
        .contextModule(new ContextModule(getContext()))
        .build();
bbcSportFragmentComponent.injectBBCSportFragment(BBCSportFragment.this);

然后，应将Dagger应该注入的字段注释为@Inject。否则bbcSportFragmentComponent.injectBBCSportFragment将成功执行任何操作。

然后，Dagger文档建议使用injecting a Fragment inside onAttach before super.onAttach()。

java.lang.ClassCastException：edgar.yodgorbek.sportnews.component.DaggerApplicationComponent吗？

1 个答案: