get data through Api using Retrofit and set Data at view cart

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_margin="20dp"
        >
        <Button
            android:id="@+id/btn"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Get Data"
            android:layout_weight="1"
            android:onClick="getData"/>
        <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Userid:"
            android:layout_weight="1"
            android:paddingLeft="20dp"
            android:textSize="20dp"/>
        <EditText
            android:id="@+id/EdittextView"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:paddingLeft="20dp"
            android:inputType="number"
            android:hint="id"/>
        <Button
            android:id="@+id/btndelete"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Delete"
            android:layout_weight="1"
            android:onClick="Delete"/>
    </LinearLayout>

    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/catView"
        android:id="@+id/recycale"/>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <TextView
            android:id="@+id/text_view_result"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#000000"

            />
    </android.support.v4.widget.NestedScrollView>


</LinearLayout>

Adabterpost.java

package com.example.mostafa.jsonretrofit;

import android.content.Context;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.annotation.RequiresApi;
import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

import java.text.ParseException;

import java.util.List;

public class Adabterpost extends RecyclerView.Adapter<Adabterpost.PostViewholder>{

    private Context mCtx;
    private List<Post>postList;


    public Adabterpost(Context mCtx, List<Post> postList)throws ParseException {
        this.mCtx =mCtx;
        this.postList =postList;
    }

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

    @Override
    public void onBindViewHolder(@NonNull final PostViewholder holder,final int position) {
        final Post post = postList.get(position);


        holder.textViewid.setText(String.valueOf(post.getId()));
        holder.textViewuserid.setText(String.valueOf(post.getUserId()));
        holder.textViewtitle.setText(post.getTitle());
        holder.textViewbody.setText(post.getText());

    }

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

    public class PostViewholder extends RecyclerView.ViewHolder {
        TextView textViewid,textViewuserid,textViewtitle,textViewbody;
        public PostViewholder(View itemView) {
            super(itemView);
            textViewid = itemView.findViewById(R.id.id);
            textViewuserid= itemView.findViewById(R.id.userid);
            textViewtitle = itemView.findViewById(R.id.title);
            textViewbody = itemView.findViewById(R.id.body);


        }
    }
}

Android with api and view cart

build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "com.example.mostafa.jsonretrofit"
        minSdkVersion 19
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    // Retofit
    //implementation 'com.squareup.retrofit2:retrofit:2.4.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.4.0'
    // recyclerview
    implementation 'com.android.support:recyclerview-v7:27.0.0'
    // cardview
    implementation 'com.android.support:cardview-v7:27.+'



}

cardview.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:CardView="http://schemas.android.com/tools"
    app:cardCornerRadius="5dp"
    app:cardElevation="8dp"
    app:cardBackgroundColor="#fff"
    app:cardUseCompatPadding="true"
    android:id="@+id/cardss"
    CardView:cardCornerRadius="20dp">

    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:orientation="vertical">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:padding="4dp">

            <TextView
                android:id="@+id/id"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="id"
                android:textColor="#000"
                android:textSize="15dp" />
            <TextView
                android:id="@+id/userid"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="userid"
                android:textColor="#000"
                android:textSize="15dp" />
            <TextView
                android:id="@+id/title"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="title"
                android:textColor="#000"
                android:textSize="15dp" />
            <TextView
                android:id="@+id/body"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="body"
                android:textColor="#000"
                android:textSize="15dp" />

        </LinearLayout>

    </LinearLayout>
</android.support.v7.widget.CardView>

JsonplaceHolderApi.java

package com.example.mostafa.jsonretrofit;

import java.util.List;

import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;

public interface JsonplaceHolderApi   {


    // create one method that return Call Object
    /**
     *  this is what we want to get back from this car
     *  a list of posts which is a json array of posts
     *  json objects that we saw
     */
    //@GET("posts") // posts is relative URL  from here (https://jsonplaceholder.typicode.com/posts)
    //Call<List<Post>>getPosts();
    @GET("posts") // posts is relative URL  from here (https://jsonplaceholder.typicode.com/posts?=Number)
    Call<List<Post>> getPosts(@Query("userId")int userId);
}

MainActivity.java

package com.example.mostafa.jsonretrofit;

import android.os.Build;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;


public class MainActivity extends AppCompatActivity {
    private TextView textviewResult;
    private EditText editText;
    private int useridnumber;
    private  List<Post> posts ;
    private Adabterpost adabter;
    RecyclerView recyclerMain;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textviewResult = findViewById(R.id.text_view_result);

        recyclerMain=findViewById(R.id.recycale);
        recyclerMain.setLayoutManager(new LinearLayoutManager(this));
        recyclerMain.setHasFixedSize(true);

    }
    public void  getposts(){  // to executr our network request
        editText = findViewById(R.id.EdittextView);
        useridnumber =Integer.parseInt(editText.getText().toString());





        //Call<List<Post>> call = jsonplaceHolderApi.getPosts(useridnumber);
        Call<List<Post>> call = RetrofitClient.getInstance().getApi().getPosts(useridnumber);
        call.enqueue(new Callback<List<Post>>() {
            @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
            @Override
            public void onResponse(Call<List<Post>> call, Response<List<Post>> response) {

                // check respons is successful
                if (!response.isSuccessful()) {
                    textviewResult.setText("Code: " + response.code());
                    return;

                }

                // here actuly Data that we want from web serves
                posts = response.body();
                if(posts == null){
                    Toast.makeText(getApplicationContext(),"its null list",Toast.LENGTH_SHORT).show();
                }
                try {
                    adabter = new Adabterpost(getApplicationContext(),posts);
                } catch (ParseException e) {
                    e.printStackTrace();
                }

                recyclerMain.setLayoutManager(new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL));


                recyclerMain.setAdapter(adabter);

                // here we will display this data in textview
                /*
                for(Post post : posts){

                    String content = "";
                    content+= "ID: "+ post.getId()+"\n";
                    content+= "User ID: "+ post.getUserId()+"\n";
                    content+= "Title: "+ post.getTitle()+"\n";
                    content+= "Body: "+ post.getText()+"\n\n";

                    textviewResult.append(content);
                    */


            }

            @Override
            public void onFailure(Call<List<Post>> call, Throwable t) {
                textviewResult.setText(t.getMessage());

            }


        });

    }
    public void  getData(View view){
        getposts();

    }
    public void Delete(View view){
        //ToDo
    }

}

manifests

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.mostafa.jsonretrofit">

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Post.java

package com.example.mostafa.jsonretrofit;

import com.google.gson.annotations.SerializedName;

import java.util.ArrayList;
import java.util.List;

public class Post {

    // here  name of json value
    private  int userId ;
    private  int id;
    private  String title;
    private List<Post> post;

    public List<Post> getPost() {
        return post;
    }

    @SerializedName("body")
    private String text;

    // Getter methods
    public int getUserId() {
        return userId;
    }

    public int getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public String getText() {
        return text;
    }
}

RetrofitClient.java

package com.example.mostafa.jsonretrofit;


import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class RetrofitClient {
    private static final String BASURL="https://jsonplaceholder.typicode.com/";
    private Retrofit retrofit;
    private  static  RetrofitClient mInstance;

    public RetrofitClient() {
        // below we will execute our actual get request
        // this retrofit instance we can now create our json placeholder api
        retrofit = new Retrofit.Builder()
                .baseUrl(BASURL)
                // this is how we define that we want to use json to a pass the response
                .addConverterFactory(GsonConverterFactory.create())
                .build();


    }

    public  static  synchronized RetrofitClient getInstance(){

        if(mInstance == null){
            mInstance = new RetrofitClient();

        }
        return mInstance;
    }

    public  JsonplaceHolderApi getApi(){

        return retrofit.create(JsonplaceHolderApi.class);
    }


}