How to get a specific value from a JSON file based on another value in the JSON object in Android Studio - Java

Question

I'm trying to put together a Mock API for my app in Android Studio using JSON, and I am trying to work out how to get a specific value from the JSON file?

For example, I want to the get the "horoscope" string from the array "horoscopes" where the "sunsign" string equals "aries".

This could be super simple, but I'm not too sure where to start.

Here's my JSON:

  "horoscopes": [
    {
      "horoscopeId": 1,
      "sunsign": "aquarius",
      "month": "january",
      "horoscope": "I am the january horoscope for aquarius",
    },
    {
      "horoscopeId": 2,
      "sunsign": "pisces",
      "month": "january",
      "horoscope": "I am the january horoscope for pisces",
    },
    {
      "horoscopeId": 3,
      "sunsign": "aries",
      "month": "january",
      "horoscope": "I am the january horoscope for aries",
    },
    {
      "horoscopeId": 4,
      "sunsign": "taurus",
      "month": "january",
      "horoscope": "I am the january horoscope for taurus",
    },
    {
      "horoscopeId": 5,
      "sunsign": "gemini",
      "month": "january",
      "horoscope": "I am the january horoscope for gemini",
    },
    {
      "horoscopeId": 6,
      "sunsign": "cancer",
      "month": "january",
      "horoscope": "I am the january horoscope for cancer",
    },
    {
      "horoscopeId": 7,
      "sunsign": "leo",
      "month": "january",
      "horoscope": "I am the january horoscope for leo",
    },
    {
      "horoscopeId": 8,
      "sunsign": "virgo",
      "month": "january",
      "horoscope": "I am the january horoscope for virgo",
    },
    {
      "horoscopeId": 9,
      "sunsign": "libra",
      "month": "january",
      "horoscope": "I am the january horoscope for libra",
    },
    {
      "horoscopeId": 10,
      "sunsign": "scorpio",
      "month": "january",
      "horoscope": "I am the january horoscope for scorpio",
    },
    {
      "horoscopeId": 11,
      "sunsign": "sagittarius",
      "month": "january",
      "horoscope": "I am the january horoscope for sagittarius",
    },
    {
      "horoscopeId": 12,
      "sunsign": "capricorn",
      "month": "january",
      "horoscope": "I am the january horoscope for capricorn",
    }
 ]
}

Here's what I've got so far for connecting to the JSON:

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

public class horoscope extends AppCompatActivity {

    ArrayList<String> horoscope_al = new ArrayList<>();

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

        
        try {
            JSONObject obj = new JSONObject(loadJSONFromAsset());
            JSONArray horoscopeArray = obj.getJSONArray("horoscopes");
            for (int i = 0; i < horoscopeArray.length(); i++) {
                JSONObject horoscopeValues = horoscopeArray.getJSONObject(i);
                horoscope_al.add(horoscopeValues.getString("horoscope"));
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    public String loadJSONFromAsset()
    {
        String json_string = null;
        try {
            InputStream inpSt = getAssets().open("horoscope_api.json");
            int s = inpSt.available();
            byte[] buffer_byte = new byte[s];
            inpSt.read(buffer_byte);
            inpSt.close();
            json_string = new String(buffer_byte, "UTF-8");
        } catch (IOException ex) {
            ex.printStackTrace();
            return null;
        }
        return json_string;
    }
}

UPDATED CODE

import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class horoscope extends AppCompatActivity {

    Button back_btn;
    TextView horoscope_txt;
    String al_string = " ";

    ArrayList<String> horoscope_al = new ArrayList<>();
    @RequiresApi(api = Build.VERSION_CODES.N)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_horoscope);

        horoscope_txt = (TextView)findViewById(R.id.horoscope_txt);
        back_btn = (Button)findViewById(R.id.back_btn);
        back_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent back_intent = new Intent(horoscope.this, menu.class);
                startActivity(back_intent);
            }
        });


       try {
            JSONObject obj = new JSONObject(loadJSONFromAsset());
            JSONArray horoscopeArray = obj.getJSONArray("horoscopes");

            List<String> horoscopesOfAries = IntStream.range(0, horoscopeArray.length())
                    .mapToObj(horoscopeArray::getJSONObject)
                    .filter(horoscopeJson -> horoscopeJson.getString("sunsign").equals("aries"))
                    .map(horoscopeJson -> horoscopeJson.getString("horoscope"))
                    .collect(Collectors.toList());

            /*for (int i = 0; i < horoscopeArray.length(); i++) {
                JSONObject horoscopeValues = horoscopeArray.getJSONObject(i);
                horoscope_al.add(horoscopeValues.getString("horoscope"));
                al_string += horoscope_al.get(i);
            }*/
        } catch (JSONException e) {
            e.printStackTrace();
        }

        //horoscope_txt.setText(al_string);
    }

    public String loadJSONFromAsset()
    {
        String json_string = null;
        try {
            InputStream inpSt = getAssets().open("horoscope_api.json");
            int s = inpSt.available();
            byte[] buffer_byte = new byte[s];
            inpSt.read(buffer_byte);
            inpSt.close();
            json_string = new String(buffer_byte, "UTF-8");
        } catch (IOException ex) {
            ex.printStackTrace();
            return null;
        }
        return json_string;
    }
}

Answer 1

You can do the following:

JSONObject obj = new JSONObject(loadJSONFromAsset());
JSONArray horoscopeArray = obj.getJSONArray("horoscopes");

List<String> horoscopesOfAries = IntStream.range(0, horoscopeArray.length())
        .mapToObj(horoscopeArray::getJSONObject)
        .filter(horoscopeJson -> horoscopeJson.getString("sunsign").equals("aries"))
        .map(horoscopeJson -> horoscopeJson.getString("horoscope"))
        .collect(Collectors.toList());

Output:

[I am the january horoscope for aries]