Это правильный способ реализации переработчика?

Question

Я работаю с restful API, используя модернизацию, в данных, которые мне нужны, много объектов, поэтому я решил использовать RecyclerView, потому что он гораздо более мощный и гибкий, но это первый раз, когда я использую настроенный RecyclerView, и я не знаю, если это правильный способ использовать его в любом случае это то, что я сделал, но приложение не запустится!

Allcountries. java

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.widget.TextView;

import com.google.android.gms.common.GooglePlayServicesNotAvailableException;
import com.google.android.gms.common.GooglePlayServicesRepairableException;
import com.google.android.gms.security.ProviderInstaller;

import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.util.List;

import javax.net.ssl.SSLContext;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class Allcountries extends AppCompatActivity {

    RecyclerView recyclerView;
    TextView textViewResult;


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

        try {
            ProviderInstaller.installIfNeeded(getApplicationContext());
            SSLContext sslContext;
            sslContext = SSLContext.getInstance("TLSv1.2");
            sslContext.init(null, null, null);
            sslContext.createSSLEngine();
        } catch (GooglePlayServicesRepairableException | GooglePlayServicesNotAvailableException
                | NoSuchAlgorithmException | KeyManagementException e) {
            e.printStackTrace();
        }

        textViewResult = findViewById(R.id.countryname);
        recyclerView = findViewById(R.id.rv);

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://siteweb/")
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        CoronaLmaoNinjaCountries coronaLmaoNinjaCountries = retrofit.create(CoronaLmaoNinjaCountries.class);

        Call<List<Detail>> call = coronaLmaoNinjaCountries.getPosts();

        call.enqueue(new Callback<List<Detail>>() {
            @Override
            public void onResponse(Call<List<Detail>> call, Response<List<Detail>> response) {

                if (!response.isSuccessful()) {
                    textViewResult.setText("Code: " + response.code());
                    return;
                }

                List<Detail> details = response.body();
                DetailAdapter detailAdapter = new DetailAdapter(Allcountries.this,details);
                recyclerView.setAdapter(detailAdapter);
                recyclerView.setLayoutManager(new LinearLayoutManager(Allcountries.this));
            }
            @Override
            public void onFailure(Call<List<Detail>> call, Throwable t) {
                textViewResult.setText(t.getMessage());
            }
        });
    }}

DetailAdapter. java

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class DetailAdapter extends RecyclerView.Adapter<DetailAdapter.MyViewHolder>{

    List<Detail> countries;
    Context ct;

    public DetailAdapter(Context ct,List<Detail> countries) {
        this.countries = countries;
        this.ct=ct;

    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(ct);
        View view = inflater.inflate(R.layout.row, parent, false);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        holder.country.setText(countries.get(position).getCountry());
        holder.cases.setText(countries.get(position).getCases());
        holder.recovered.setText(countries.get(position).getRecovered());
        holder.deaths.setText(countries.get(position).getDeaths());

    }

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

    public class MyViewHolder extends RecyclerView.ViewHolder{

        TextView country,cases,recovered,deaths;
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            country = itemView.findViewById(R.id.countryname);
            cases = itemView.findViewById(R.id.cases);
            recovered = itemView.findViewById(R.id.recovered);
            deaths = itemView.findViewById(R.id.deathsr);
        }
    }
}

Detail. java

public class Detail {
    private String country;
    private int cases;
    private int deaths;
    private int recovered;

    public String getCountry() {
        return country;
    }

    public int getCases() {
        return cases;
    }


    public int getDeaths() {
        return deaths;
    }


    public int getRecovered() {
        return recovered;
    }

} 

Activity_Allcountries. xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Allcountries">


<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/rv"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />



</androidx.constraintlayout.widget.ConstraintLayout> 

ряд. xml

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <androidx.cardview.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        tools:ignore="MissingConstraints">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/countryname"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginBottom="21dp"
                android:text="TextView"
                app:layout_constraintBottom_toTopOf="@+id/deathsr"
                tools:layout_editor_absoluteX="176dp" />

            <TextView
                android:id="@+id/cases"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginEnd="101dp"
                android:layout_marginRight="101dp"
                android:text="TextView"
                app:layout_constraintEnd_toStartOf="@+id/deathsr"
                tools:layout_editor_absoluteY="40dp" />

            <TextView
                android:id="@+id/recovered"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginStart="101dp"
                android:layout_marginLeft="101dp"
                android:text="TextView"
                app:layout_constraintStart_toEndOf="@+id/deathsr"
                tools:layout_editor_absoluteY="40dp" />

            <TextView
                android:id="@+id/deathsr"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="TextView"
                tools:layout_editor_absoluteX="176dp"
                tools:layout_editor_absoluteY="40dp" />

        </androidx.constraintlayout.widget.ConstraintLayout>

    </androidx.cardview.widget.CardView>
</androidx.constraintlayout.widget.ConstraintLayout>``` ```

CoronaLmaoNinjaCountries. java

import java.util.List;
import retrofit2.Call;
import retrofit2.http.GET;

public interface CoronaLmaoNinjaCountries {
    @GET("countries")
    Call<List<Detail>> getPosts();
}

ошибка logcat:

example.testcor E/dalvikvm: Could not find class 'androidx.core.view.ViewCompat$2', referenced from method androidx.core.view.ViewCompat.addOnUnhandledKeyEventListener
03-16 12:46:51.237 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'android.view.WindowInsets', referenced from method androidx.core.view.ViewCompat.dispatchApplyWindowInsets
03-16 12:46:51.267 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'android.view.WindowInsets', referenced from method androidx.core.view.ViewCompat.onApplyWindowInsets
03-16 12:46:51.267 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'android.view.View$OnUnhandledKeyEventListener', referenced from method androidx.core.view.ViewCompat.removeOnUnhandledKeyEventListener
03-16 12:46:51.277 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'androidx.core.view.ViewCompat$1', referenced from method androidx.core.view.ViewCompat.setOnApplyWindowInsetsListener
03-16 12:46:51.317 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method androidx.appcompat.widget.AppCompatImageHelper.hasOverlappingRendering
03-16 12:46:51.417 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'android.view.textclassifier.TextClassificationManager', referenced from method androidx.appcompat.widget.AppCompatTextClassifierHelper.getTextClassifier
03-16 12:46:51.487 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'android.app.AppOpsManager', referenced from method com.google.android.gms.common.wrappers.PackageManagerWrapper.zzb
03-16 12:46:51.578 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'android.app.AppOpsManager', referenced from method off.a
03-16 12:46:51.588 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'com.google.android.gms.org.conscrypt.TrustManagerImpl', referenced from method com.google.android.gms.org.conscrypt.Conscrypt.isConscrypt
03-16 12:46:51.598 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'com.google.android.gms.org.conscrypt.TrustManagerImpl', referenced from method com.google.android.gms.org.conscrypt.Conscrypt.toConscrypt
03-16 12:46:51.818 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'javax.net.ssl.SNIServerName', referenced from method com.google.android.gms.org.conscrypt.Platform.getSniHostnameFromParams
03-16 12:46:51.818 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'javax.net.ssl.SNIHostName', referenced from method com.google.android.gms.org.conscrypt.Platform.setParametersSniHostname
03-16 12:46:51.818 8193-8193/com.example.testcor E/dalvikvm: Could not find class 'javax.net.ssl.SNIHostName', referenced from method com.google.android.gms.org.conscrypt.Platform.setParametersSniHostname
03-16 12:46:52.318 8193-8193/com.example.testcor E/RecyclerView: No adapter attached; skipping layout
03-16 12:46:52.358 8193-8193/com.example.testcor E/AndroidRuntime: FATAL EXCEPTION: main
    java.lang.NullPointerException
        at com.example.testcor.Allcountries$1.onFailure(Allcountries.java:77)
        at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$2.run(ExecutorCallAdapterFactory.java:79)
        at android.os.Handler.handleCallback(Handler.java:725)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:176)
        at android.app.ActivityThread.main(ActivityThread.java:5299)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
        at dalvik.system.NativeStart.main(Native Method)

Answer 1

Сначала убедитесь, что вы правильно выполнили синтаксический анализ JSON, используйте @SerializedName ("key_name") и задайте для него имя ключа. Затем убедитесь, что вы выполнили правильную инициализацию для recyclerView

1 - init recyclerview

RecyclerView recyclerView = findViewById(R.id.rv);

2 - установите LayoutManager

recyclerView.setLayoutManager(new LinearLayoutManager(this)); //(Required)

3 - создайте адаптер и передайте его в recyclerview

recyclerView.setAdapter(adapter);