L10: RecyclerView with multiple view types

AOrobator · Mar 4, 2019 · a3f7878 · a3f7878
1 parent e37d4d2
commit a3f7878
Show file tree

Hide file tree

Showing 19 changed files with 517 additions and 53 deletions.
diff --git a/lesson10/Lesson10_RecyclerView.md b/lesson10/Lesson10_RecyclerView.md
@@ -250,6 +250,21 @@ protected void onCreate(Bundle savedInstanceState) {
 }
 ```
 
+## Handling multiple view types
+
+In the `AnswersActivity`, create a RecyclerView where the adapter has 2 view types, a `Question` and 
+an `Answer`. You'll have to override `getItemViewType` in your adapter. The first item should be the
+`Question` and the remaining items should be the `Answer`s. I'd also recommend making an abstract 
+`ViewHolder` that the 2 view types extend from. That way you can declare your adapter like:
+
+```java
+public class AnswersRecyclerAdapter extends RecyclerView.ViewHolder<YourAbstractViewHolderClass> { ... }
+```
+
+Your end product should look something like this:
+
+![Answers View][answers_view]
 
 [StackOverflow]: StackOverflow.jpg "StackOverflow"
 [StackOverflow API]: https://api.stackexchange.com/docs
+[answers_view]: answers_view.jpg "Answers View"
diff --git a/lesson10/answers_view.jpg b/lesson10/answers_view.jpg
diff --git a/lesson10/src/main/AndroidManifest.xml b/lesson10/src/main/AndroidManifest.xml
@@ -14,7 +14,7 @@
       android:supportsRtl="true"
       android:theme="@style/AppTheme"
       tools:ignore="GoogleAppIndexingWarning">
-    <activity android:name=".answers.AnswersActivity"/>
+    <activity android:name=".answers.view.AnswersActivity"/>
     <activity android:name=".questions.view.QuestionsActivity">
       <intent-filter>
         <action android:name="android.intent.action.MAIN"/>

diff --git a/lesson10/src/main/java/com/orobator/helloandroid/lesson10/answers/AnswersActivity.java b/lesson10/src/main/java/com/orobator/helloandroid/lesson10/answers/AnswersActivity.java
diff --git a/...10/src/main/java/com/orobator/helloandroid/lesson10/answers/di/AnswersActivityModule.java b/...10/src/main/java/com/orobator/helloandroid/lesson10/answers/di/AnswersActivityModule.java
@@ -1,5 +1,7 @@
 package com.orobator.helloandroid.lesson10.answers.di;
 
+import com.orobator.helloandroid.common.AppSchedulers;
+import com.orobator.helloandroid.lesson10.answers.viewmodel.AnswersViewModelFactory;
 import com.orobator.helloandroid.stackoverflow.answers.AnswersApi;
 import com.orobator.helloandroid.stackoverflow.answers.AnswersRepository;
 import com.orobator.helloandroid.stackoverflow.answers.AnswersRepositoryImpl;
@@ -18,4 +20,11 @@ public AnswersApi provideAnswersApi(Retrofit retrofit) {
   public AnswersRepository provideAnswersRepository(AnswersApi answersApi) {
     return new AnswersRepositoryImpl(answersApi);
   }
+
+  @Provides
+  public AnswersViewModelFactory provideAnswersViewModelFactory(
+      AnswersRepository answersRepository,
+      AppSchedulers schedulers) {
+    return new AnswersViewModelFactory(answersRepository, schedulers);
+  }
 }
diff --git a/lesson10/src/main/java/com/orobator/helloandroid/lesson10/answers/view/AnswersActivity.java b/lesson10/src/main/java/com/orobator/helloandroid/lesson10/answers/view/AnswersActivity.java
@@ -0,0 +1,59 @@
+package com.orobator.helloandroid.lesson10.answers.view;
+
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.databinding.DataBindingUtil;
+import androidx.lifecycle.Observer;
+import androidx.lifecycle.ViewModelProviders;
+import com.orobator.helloandroid.lesson10.R;
+import com.orobator.helloandroid.lesson10.answers.viewmodel.AnswerViewModel;
+import com.orobator.helloandroid.lesson10.answers.viewmodel.AnswersViewModel;
+import com.orobator.helloandroid.lesson10.answers.viewmodel.AnswersViewModelFactory;
+import com.orobator.helloandroid.lesson10.databinding.ActivityAnswersBinding;
+import com.orobator.helloandroid.lesson10.questions.viewmodel.QuestionViewModel;
+import com.orobator.helloandroid.stackoverflow.questions.Question;
+import dagger.android.AndroidInjection;
+import java.util.List;
+import javax.inject.Inject;
+
+public class AnswersActivity extends AppCompatActivity implements Observer<List<AnswerViewModel>> {
+  private static final String KEY_QUESTION = "question";
+
+  public static Intent getIntent(Context context, Question question) {
+    Intent intent = new Intent(context, AnswersActivity.class);
+    intent.putExtra(KEY_QUESTION, question);
+    return intent;
+  }
+
+  private AnswersRecyclerAdapter adapter;
+
+  @Inject AnswersViewModelFactory viewModelFactory;
+
+  @Override
+  protected void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    AndroidInjection.inject(this);
+
+    ActivityAnswersBinding binding =
+        DataBindingUtil.setContentView(this, R.layout.activity_answers);
+
+    AnswersViewModel viewModel =
+        ViewModelProviders
+            .of(this, viewModelFactory)
+            .get(AnswersViewModel.class);
+
+    Question question = getIntent().getParcelableExtra(KEY_QUESTION);
+    viewModel.setQuestion(question);
+
+    viewModel.getAnswerViewModelsLiveData().observe(this, this);
+
+    adapter = new AnswersRecyclerAdapter(new QuestionViewModel(question));
+    binding.answersRecyclerView.setAdapter(adapter);
+  }
+
+  @Override public void onChanged(List<AnswerViewModel> answerViewModels) {
+    adapter.updateList(answerViewModels);
+  }
+}
diff --git a/...src/main/java/com/orobator/helloandroid/lesson10/answers/view/AnswersRecyclerAdapter.java b/...src/main/java/com/orobator/helloandroid/lesson10/answers/view/AnswersRecyclerAdapter.java
@@ -0,0 +1,110 @@
+package com.orobator.helloandroid.lesson10.answers.view;
+
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import androidx.annotation.NonNull;
+import androidx.databinding.DataBindingUtil;
+import androidx.recyclerview.widget.RecyclerView;
+import com.orobator.helloandroid.lesson10.R;
+import com.orobator.helloandroid.lesson10.answers.view.AnswersRecyclerAdapter.QuestionDetailViewHolder;
+import com.orobator.helloandroid.lesson10.answers.viewmodel.AnswerViewModel;
+import com.orobator.helloandroid.lesson10.databinding.ListItemAnswerBinding;
+import com.orobator.helloandroid.lesson10.databinding.ListItemQuestionDetailBinding;
+import com.orobator.helloandroid.lesson10.questions.viewmodel.QuestionViewModel;
+import java.util.Collections;
+import java.util.List;
+
+public class AnswersRecyclerAdapter extends RecyclerView.Adapter<QuestionDetailViewHolder> {
+  private static final int VIEW_TYPE_QUESTION = 0;
+  private static final int VIEW_TYPE_ANSWER = 1;
+
+  private List<AnswerViewModel> answerViewModels = Collections.emptyList();
+  private final QuestionViewModel questionViewModel;
+
+  public AnswersRecyclerAdapter(QuestionViewModel questionViewModel) {
+    this.questionViewModel = questionViewModel;
+  }
+
+  @Override public int getItemViewType(int position) {
+    if (position == 0) {
+      return VIEW_TYPE_QUESTION;
+    } else {
+      return VIEW_TYPE_ANSWER;
+    }
+  }
+
+  @Override public int getItemCount() {
+    return 1 + answerViewModels.size();
+  }
+
+  @NonNull @Override
+  public QuestionDetailViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+    if (viewType == VIEW_TYPE_QUESTION) {
+      return onCreateQuestionViewHolder(parent);
+    } else {
+      return onCreateAnswerViewHolder(parent);
+    }
+  }
+
+  private QuestionViewHolder onCreateQuestionViewHolder(ViewGroup parent) {
+    LayoutInflater inflater = LayoutInflater.from(parent.getContext());
+    ListItemQuestionDetailBinding binding =
+        DataBindingUtil.inflate(inflater, R.layout.list_item_question_detail, parent, false);
+    return new QuestionViewHolder(binding);
+  }
+
+  private QuestionDetailViewHolder onCreateAnswerViewHolder(ViewGroup parent) {
+    LayoutInflater inflater = LayoutInflater.from(parent.getContext());
+    ListItemAnswerBinding binding =
+        DataBindingUtil.inflate(inflater, R.layout.list_item_answer, parent, false);
+    return new AnswerViewHolder(binding);
+  }
+
+  @Override public void onBindViewHolder(@NonNull QuestionDetailViewHolder holder, int position) {
+    if (getItemViewType(position) == VIEW_TYPE_QUESTION) {
+      ((QuestionViewHolder) holder).bind(questionViewModel);
+    } else {
+      ((AnswerViewHolder) holder).bind(answerViewModels.get(position - 1));
+    }
+  }
+
+  public void updateList(List<AnswerViewModel> answerViewModels) {
+    this.answerViewModels = answerViewModels;
+    notifyDataSetChanged();
+  }
+
+  static abstract class QuestionDetailViewHolder extends RecyclerView.ViewHolder {
+    public QuestionDetailViewHolder(@NonNull View itemView) {
+      super(itemView);
+    }
+  }
+
+  static class QuestionViewHolder extends QuestionDetailViewHolder {
+    private final ListItemQuestionDetailBinding binding;
+
+    public QuestionViewHolder(ListItemQuestionDetailBinding binding) {
+      super(binding.getRoot());
+
+      this.binding = binding;
+    }
+
+    public void bind(QuestionViewModel questionViewModel) {
+      binding.setVm(questionViewModel);
+    }
+  }
+
+  static class AnswerViewHolder extends QuestionDetailViewHolder {
+    private final ListItemAnswerBinding binding;
+
+    public AnswerViewHolder(ListItemAnswerBinding binding) {
+      super(binding.getRoot());
+
+      this.binding = binding;
+    }
+
+    public void bind(AnswerViewModel answerViewModel) {
+      binding.setVm(answerViewModel);
+    }
+  }
+}
diff --git a/...0/src/main/java/com/orobator/helloandroid/lesson10/answers/viewmodel/AnswerViewModel.java b/...0/src/main/java/com/orobator/helloandroid/lesson10/answers/viewmodel/AnswerViewModel.java
@@ -0,0 +1,19 @@
+package com.orobator.helloandroid.lesson10.answers.viewmodel;
+
+import android.text.Spanned;
+import androidx.core.text.HtmlCompat;
+import com.orobator.helloandroid.stackoverflow.answers.Answer;
+
+import static androidx.core.text.HtmlCompat.FROM_HTML_MODE_LEGACY;
+
+public class AnswerViewModel {
+  public final Spanned body;
+  public final String voteCount;
+  public final String userName;
+
+  public AnswerViewModel(Answer answer) {
+    body = HtmlCompat.fromHtml(answer.body, FROM_HTML_MODE_LEGACY);
+    voteCount = Integer.toString(answer.score);
+    userName = answer.owner.getDisplayName();
+  }
+}
diff --git a/.../src/main/java/com/orobator/helloandroid/lesson10/answers/viewmodel/AnswersViewModel.java b/.../src/main/java/com/orobator/helloandroid/lesson10/answers/viewmodel/AnswersViewModel.java
@@ -0,0 +1,62 @@
+package com.orobator.helloandroid.lesson10.answers.viewmodel;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import com.orobator.helloandroid.common.AppSchedulers;
+import com.orobator.helloandroid.observableviewmodel.ObservableViewModel;
+import com.orobator.helloandroid.stackoverflow.answers.Answer;
+import com.orobator.helloandroid.stackoverflow.answers.AnswersRepository;
+import com.orobator.helloandroid.stackoverflow.answers.AnswersResponse;
+import com.orobator.helloandroid.stackoverflow.questions.Question;
+import io.reactivex.disposables.Disposable;
+import java.util.ArrayList;
+import java.util.List;
+
+public class AnswersViewModel extends ObservableViewModel {
+  private final AnswersRepository answersRepository;
+  private final AppSchedulers schedulers;
+  private Disposable disposable;
+  private MutableLiveData<List<AnswerViewModel>> answerViewModelsLiveData = new MutableLiveData<>();
+
+  public AnswersViewModel(
+      AnswersRepository answersRepository,
+      AppSchedulers schedulers) {
+    this.answersRepository = answersRepository;
+    this.schedulers = schedulers;
+  }
+
+  public void setQuestion(Question question) {
+    disposable = answersRepository
+        .getAnswersForQuestion(question.getQuestionId())
+        .subscribeOn(schedulers.io)
+        .observeOn(schedulers.main)
+        .subscribe(this::onGetAnswersSuccess, this::onGetAnswersError);
+  }
+
+  public LiveData<List<AnswerViewModel>> getAnswerViewModelsLiveData() {
+    return answerViewModelsLiveData;
+  }
+
+  private void onGetAnswersSuccess(AnswersResponse response) {
+    List<AnswerViewModel> answerViewModels = new ArrayList<>(response.answers.size());
+
+    for (Answer answer : response.answers) {
+      answerViewModels.add(new AnswerViewModel(answer));
+    }
+
+    answerViewModelsLiveData.setValue(answerViewModels);
+  }
+
+  private void onGetAnswersError(Throwable throwable) {
+    // Ignored for simplicity. See Lesson 9 for error handling
+  }
+
+  @Override protected void onCleared() {
+    super.onCleared();
+
+    if (disposable != null) {
+      disposable.dispose();
+      disposable = null;
+    }
+  }
+}
diff --git a/...in/java/com/orobator/helloandroid/lesson10/answers/viewmodel/AnswersViewModelFactory.java b/...in/java/com/orobator/helloandroid/lesson10/answers/viewmodel/AnswersViewModelFactory.java
@@ -0,0 +1,23 @@
+package com.orobator.helloandroid.lesson10.answers.viewmodel;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.ViewModel;
+import androidx.lifecycle.ViewModelProvider;
+import com.orobator.helloandroid.common.AppSchedulers;
+import com.orobator.helloandroid.stackoverflow.answers.AnswersRepository;
+
+public class AnswersViewModelFactory implements ViewModelProvider.Factory {
+  private final AnswersRepository answersRepository;
+  private final AppSchedulers schedulers;
+
+  public AnswersViewModelFactory(
+      AnswersRepository answersRepository,
+      AppSchedulers schedulers) {
+    this.answersRepository = answersRepository;
+    this.schedulers = schedulers;
+  }
+
+  @NonNull @Override public <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
+    return (T) new AnswersViewModel(answersRepository, schedulers);
+  }
+}
diff --git a/lesson10/src/main/java/com/orobator/helloandroid/lesson10/di/ActivityBindingModule.java b/lesson10/src/main/java/com/orobator/helloandroid/lesson10/di/ActivityBindingModule.java
@@ -1,7 +1,7 @@
 package com.orobator.helloandroid.lesson10.di;
 
-import com.orobator.helloandroid.lesson10.answers.AnswersActivity;
 import com.orobator.helloandroid.lesson10.answers.di.AnswersActivityModule;
+import com.orobator.helloandroid.lesson10.answers.view.AnswersActivity;
 import com.orobator.helloandroid.lesson10.questions.di.QuestionsActivityModule;
 import com.orobator.helloandroid.lesson10.questions.view.QuestionsActivity;
 import dagger.Module;

diff --git a/...10/src/main/java/com/orobator/helloandroid/lesson10/questions/view/QuestionsActivity.java b/...10/src/main/java/com/orobator/helloandroid/lesson10/questions/view/QuestionsActivity.java
@@ -7,7 +7,7 @@
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProviders;
 import com.orobator.helloandroid.lesson10.R;
-import com.orobator.helloandroid.lesson10.answers.AnswersActivity;
+import com.orobator.helloandroid.lesson10.answers.view.AnswersActivity;
 import com.orobator.helloandroid.lesson10.databinding.ActivityQuestionsBinding;
 import com.orobator.helloandroid.lesson10.questions.viewmodel.QuestionsViewModel;
 import com.orobator.helloandroid.lesson10.questions.viewmodel.QuestionsViewModelFactory;