How do I Read JSON file From Assets Folder Android Kotlin

Published November 25, 2021

In this Android Example tutorial we will cover read file from assets folder and display content on the activity. To Read file from assets folder we will use AssetManager class. This class contains method open() to read content from the file.

Here we will pas the file name as attribute.

Let's get started

Step 1: Create android project in Android Studio

Step 2: Add Your JSON file inside assets folder

Assets folder structure should be like below

Step 3: Create UI to read and display JSON file

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
    <TextView
        android:id="@+id/display"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:padding="12sp"
        android:textStyle="bold"/>
    <Button
        android:id="@+id/btnReadFile"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Read text from assets"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20sp"
        android:textStyle="bold">
    </Button>
</RelativeLayout>

Step 4: Now Write function to Read File from Assets folder

fun  readFile()
  {
      try {
          val inputStream: InputStream = assets.open("assetsfile.txt")
          val size: Int = inputStream.available()
          val buffer = ByteArray(size)
          inputStream.read(buffer)
          string = String(buffer)
      } catch (e: IOException) {
          e.printStackTrace()
      }
  }

Read JSON File from Assets

fun  readJSONFile()
{
    try {
        val inputStream: InputStream = assets.open("sample.json")
        val size: Int = inputStream.available()
        val buffer = ByteArray(size)
        inputStream.read(buffer)
        string = String(buffer)
    } catch (e: IOException) {
        e.printStackTrace()
    }
}

Step 5: Now run application and tap on button, it will read file content from assets folder and display on TextView.

Complete Activity Code

package com.rrtutors.readjson

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.R.string
import android.widget.Button
import android.widget.TextView
import java.io.IOException
import java.io.InputStream


class ReadFileActivity : AppCompatActivity() {
    lateinit var  string:String
    lateinit var  display:TextView
    lateinit var  btnReadFile: Button
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_read_file)
        btnReadFile.setOnClickListener {
            readJSONFile();
            display.setText(string)
        }
    }

  fun  readFile()
    {
        try {
            val inputStream: InputStream = assets.open("assetsfile.txt")
            val size: Int = inputStream.available()
            val buffer = ByteArray(size)
            inputStream.read(buffer)
            string = String(buffer)
        } catch (e: IOException) {
            e.printStackTrace()
        }
    }

    fun  readJSONFile()
    {
        try {
            val inputStream: InputStream = assets.open("sample.json")
            val size: Int = inputStream.available()
            val buffer = ByteArray(size)
            inputStream.read(buffer)
            string = String(buffer)
        } catch (e: IOException) {
            e.printStackTrace()
        }
    }
}

Conclusion: In this Android example tutorial we covered how to read file from assets folder and display on the activity.

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