Java tutorial
/*** Copyright (c) 2013-2015 CommonsWare, LLC Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. Covered in detail in the book _The Busy Coder's Guide to Android Development_ https://commonsware.com/Android */ package com.commonsware.android.databind.basic; import android.content.Intent; import android.net.Uri; import android.os.Bundle; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v4.app.Fragment; import android.support.v7.widget.DividerItemDecoration; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.text.TextUtils; import android.util.Log; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.widget.Toast; import com.commonsware.android.databind.basic.databinding.RowBinding; import com.squareup.picasso.Picasso; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import io.reactivex.android.schedulers.AndroidSchedulers; import io.reactivex.disposables.Disposable; import io.reactivex.schedulers.Schedulers; import retrofit2.Retrofit; import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory; import retrofit2.converter.gson.GsonConverterFactory; public class QuestionsFragment extends Fragment { private ArrayList<Question> questions = new ArrayList<Question>(); private HashMap<String, Question> questionMap = new HashMap<String, Question>(); Retrofit retrofit = new Retrofit.Builder().baseUrl("https://api.stackexchange.com") .addConverterFactory(GsonConverterFactory.create()) .addCallAdapterFactory(RxJava2CallAdapterFactory.create()).build(); StackOverflowInterface so = retrofit.create(StackOverflowInterface.class); private RVQuestionsAdapter adapter; private Disposable sub; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setRetainInstance(true); setHasOptionsMenu(true); adapter = new RVQuestionsAdapter(getLayoutInflater()); } @Nullable @Override public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { return inflater.inflate(R.layout.main, container, false); } @Override public void onViewCreated(@NonNull View v, @Nullable Bundle savedInstanceState) { RecyclerView rv = v.findViewById(android.R.id.list); rv.setLayoutManager(new LinearLayoutManager(getActivity())); rv.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL)); rv.setAdapter(adapter); sub = so.questions("android").subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()) .subscribe(soQuestions -> { for (Item item : soQuestions.items) { Question question = new Question(item); questions.add(question); questionMap.put(question.id, question); } adapter.setQuestions(questions); }, t -> { Toast.makeText(getActivity(), t.getMessage(), Toast.LENGTH_LONG).show(); Log.e(getClass().getSimpleName(), "Exception from Retrofit request to StackOverflow", t); }); } @Override public void onDestroy() { unsub(); super.onDestroy(); } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.actions, menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { if (item.getItemId() == R.id.refresh) { updateQuestions(); } return (super.onOptionsItemSelected(item)); } private void updateQuestions() { ArrayList<String> idList = new ArrayList<String>(); for (Question question : questions) { idList.add(question.id); } String ids = TextUtils.join(";", idList); unsub(); sub = so.update(ids).observeOn(AndroidSchedulers.mainThread()).subscribeOn(Schedulers.io()) .subscribe(result -> { for (Item item : result.items) { Question question = questionMap.get(item.id); if (question != null) { question.updateFromItem(item); } } }, t -> { Toast.makeText(getActivity(), t.getMessage(), Toast.LENGTH_LONG).show(); Log.e(getClass().getSimpleName(), "Exception from Retrofit request to StackOverflow", t); }); } private void unsub() { if (sub != null && !sub.isDisposed()) { sub.dispose(); } } private static class RVQuestionsAdapter extends RecyclerView.Adapter<RowHolder> { private List<Question> questions; private final LayoutInflater inflater; private RVQuestionsAdapter(LayoutInflater inflater) { this.inflater = inflater; } @NonNull @Override public RowHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { RowBinding rowBinding = RowBinding.inflate(inflater, parent, false); return new RowHolder(rowBinding); } @Override public void onBindViewHolder(@NonNull RowHolder holder, int position) { holder.bind(questions.get(position)); } @Override public int getItemCount() { return questions == null ? 0 : questions.size(); } private void setQuestions(List<Question> questions) { this.questions = questions; notifyDataSetChanged(); } } private static class RowHolder extends RecyclerView.ViewHolder { private final RowBinding binding; RowHolder(RowBinding binding) { super(binding.getRoot()); this.binding = binding; } public void bind(Question question) { Picasso.with(binding.icon.getContext()).load(question.owner.profileImage).fit().centerCrop() .placeholder(R.drawable.owner_placeholder).error(R.drawable.owner_error).into(binding.icon); binding.setQuestion(question); binding.getRoot().setOnClickListener(v -> binding.icon.getContext() .startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(question.link)))); binding.executePendingBindings(); } } }