retrofit android example

different files.java

build.gradle.kts (Module):

dependencies {
    ...
    implementation("androidx.recyclerview:recyclerview:1.3.2")
    implementation("com.squareup.retrofit2:retrofit:3.0.0")
    implementation("com.squareup.retrofit2:converter-gson:3.0.0")
    implementation("com.google.code.gson:gson:2.11.0")
}

================================================================================================================
  
MainActivity.java:

package site.sunmeat.helloworld;

import android.os.*;
import android.view.*;
import android.widget.*;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.*;
import com.google.gson.annotations.*;
import java.util.*;
import java.util.concurrent.*;
import retrofit2.*;
import retrofit2.converter.gson.GsonConverterFactory;
import retrofit2.http.*;

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private ProgressBar progressBar;
    private JokeAdapter adapter;
    private final ArrayList<JokeModel> jokes = new ArrayList<>();
    private static final int TOTAL_JOKES = 20;

    // === Retrofit 3.0.0 інтерфейс ===
    public interface JokeApi {
        @GET("joke/Programming")
        Call<JokeModel> getJoke(@Query("type") String type); // параметр не обов’язковий, для сумісності
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = findViewById(R.id.posts_recycle_view);
        progressBar = findViewById(R.id.progressBar);

        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new JokeAdapter(jokes);
        recyclerView.setAdapter(adapter);

        // === Retrofit 3.0.0 ===
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://v2.jokeapi.dev/")
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        JokeApi api = retrofit.create(JokeApi.class);
        loadJokes(api);
    }

    private void loadJokes(JokeApi api) {
        ExecutorService executor = Executors.newSingleThreadExecutor();
        var mainHandler = new Handler(Looper.getMainLooper());

        executor.execute(() -> {
            int loaded = 0;

            while (loaded < TOTAL_JOKES) {
                try {
                    Call<JokeModel> call = api.getJoke(""); // або просто null
                    retrofit2.Response<JokeModel> response = call.execute();

                    if (response.isSuccessful() && response.body() != null) {
                        JokeModel joke = response.body();

                        mainHandler.post(() -> {
                            jokes.add(joke);
                            adapter.notifyItemInserted(jokes.size() - 1);
                            recyclerView.scrollToPosition(jokes.size() - 1);
                        });

                        loaded++;
                    } else {
                        // якщо помилка – трохи почекаємо і спробуємо ще раз
                        Thread.sleep(500);
                    }
                } catch (Exception e) {
                    try { Thread.sleep(1000); } catch (InterruptedException ignored) {}
                }
            }

            mainHandler.post(() -> {
                progressBar.setVisibility(View.GONE);
                if (jokes.isEmpty()) {
                    Toast.makeText(this, "Не вдалося завантажити жарти", Toast.LENGTH_LONG).show();
                }
            });

            executor.shutdown();
        });
    }

    // ==================== адаптер для списку ====================
    private static class JokeAdapter extends RecyclerView.Adapter<JokeAdapter.ViewHolder> {
        private final List<JokeModel> jokes;

        JokeAdapter(List<JokeModel> jokes) {
            this.jokes = jokes;
        }

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

        @Override
        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
            String content = jokes.get(position).getContent();
            content = content.replaceAll("! -", "\n-");
            holder.textView.setText(content);
        }

        @Override
        public int getItemCount() {
            return jokes.size();
        }

        static class ViewHolder extends RecyclerView.ViewHolder {
            TextView textView;

            ViewHolder(View itemView) {
                super(itemView);
                textView = itemView.findViewById(R.id.post);
            }
        }
    }

    // ==================== модель ====================
    public static class JokeModel {
        @SerializedName("type")
        @Expose
        private String type;

        @SerializedName("joke")
        @Expose
        private String joke;

        @SerializedName("setup")
        @Expose
        private String setup;

        @SerializedName("delivery")
        @Expose
        private String delivery;

        public String getContent() {
            if ("single".equals(type) && joke != null) {
                return joke;
            } else if ("twopart".equals(type) && setup != null && delivery != null) {
                return setup + "\n\n" + delivery;
            }
            return "Жарт не розпарсено";
        }
    }
}

================================================================================================================
  
activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#121926">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/posts_recycle_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:background="@android:color/transparent"
        android:clipToPadding="false"
        android:padding="4dp" />

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:indeterminateTint="#FFFFFF"
        android:visibility="visible" />

</RelativeLayout>

================================================================================================================

post_item.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    android:layout_marginTop="4dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="4dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:color/transparent"
        android:orientation="vertical"
        android:padding="12dp">

        <TextView
            android:id="@+id/post"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#FFFFFF"
            android:fontFamily="sans-serif"
            android:lineSpacingExtra="2dp"
            android:padding="4dp"
            android:textColor="#000000"
            android:textSize="16sp"
            android:textStyle="normal" />
    </LinearLayout>
</androidx.cardview.widget.CardView>