How to remove duplications in volley json array in android?

This example demonstrate about How to use Abstract list in volley json array in android.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/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:gravity="center"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/text"
      android:textSize="30sp"
      android:layout_width="match_parent"
      android:layout_height="match_parent" />
</LinearLayout>

In the above code, we have taken text view to show Abstract list items.

Step 3 − Add the following code to src/MainActivity.java

package com.example.myapplication;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.TextView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
public class MainActivity extends AppCompatActivity {
   TextView textView;
   RequestQueue queue;
   String URL = "http://www.mocky.io/v2/597c41390f0000d002f4dbd1";
   @RequiresApi(api = Build.VERSION_CODES.N)
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      textView = findViewById(R.id.text);
      final AbstractList<UserInfo> list=new ArrayList<>();
      queue = Volley.newRequestQueue(this);
      StringRequest request = new StringRequest(Request.Method.GET, URL, new Response.Listener<String>() {
         @Override
         public void onResponse(String response) {
            try {
               JSONObject object=new JSONObject(response);
               JSONArray array=object.getJSONArray("users");
               for(int i=0;i<array.length();i++) {
                  JSONObject object1=array.getJSONObject(i);
                  String name =object1.getString("name");
                  String id =object1.getString("id");
                  list.add(new UserInfo(name,id));
               }
               Collections.sort(list, new Comparator<UserInfo>() {
                  @Override
                  public int compare(UserInfo o1, UserInfo o2) {
                     return o1.id.compareTo(o2.id);
                  }
               });
               HashSet<UserInfo> hashSet=new HashSet<>(list);
               list.clear();
               list.addAll(hashSet);
               textView.setText("id: "+list.get(0).id+ " 
name: "+list.get(0).name);
            } catch (JSONException e) {
               e.printStackTrace();
            }
         }
      }, new Response.ErrorListener() {
         @Override
         public void onErrorResponse(VolleyError error) {
            Log.d("error",error.toString());
         }
      });
      queue.add(request);
   }
   private class UserInfo {
      String name,id;
      public UserInfo(String name, String id) {
         this.name=name;
         this.id=id;
      }
}
}

Step 4 − Add the following code to AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.myapplication">
   <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" />
            <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
</application>
</manifest>

Step 5 − Add the following code to build.gradle

apply plugin: 'com.android.application'
android {
   compileSdkVersion 28
   defaultConfig {
      applicationId "com.example.myapplication"
      minSdkVersion 15
      targetSdkVersion 28
      versionCode 1
      versionName "1.0"
      testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
   }
   buildTypes {
      release {
         minifyEnabled false
         proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
     }
   }
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.volley:volley:1.1.0'
implementation 'com.android.support:appcompat-v7:28.0.0'
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'
}

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –

Click here to download the project code