Open In App

Android Jetpack Compose External Storage

Improve
Improve
Like Article
Like
Save
Share
Report

Android device provides us with various options to store the data of the application. We can use shared preferences, external storage, and internal storage to store our data. In this article, we will take a look at How to use External storage to store the data within our android application. We will be creating a simple application to save data to the device external storage. 

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. While choosing the template, select Empty Compose Activity. If you do not find this template, try upgrading the Android Studio to the latest version. We demonstrated the application in Kotlin, so make sure you select Kotlin as the primary language while creating a New Project.

Step 2: Adding a new color in the Color.kt file

Navigate to app > java > your app’s package name > ui.theme > Color.kt file and add the below code to it. 

Kotlin




package com.example.newcanaryproject.ui.theme
 
import androidx.compose.ui.graphics.Color
 
val Purple200 = Color(0xFF0F9D58)
val Purple500 = Color(0xFF0F9D58)
val Purple700 = Color(0xFF3700B3)
val Teal200 = Color(0xFF03DAC5)
 
// on below line we are adding different colors.
val greenColor = Color(0xFF0F9D58)


Step 3: Adding permissions to read and write data to External Storage 

Navigate to app > AndroidManifest.xml file and add the below permissions to it to read and write data. 

XML




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


Step 4: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin




package com.example.newcanaryproject
 
import android.Manifest
import android.app.Activity
import android.content.*
import android.os.Bundle
import android.os.Environment
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.core.app.ActivityCompat
import com.example.newcanaryproject.ui.theme.NewCanaryProjectTheme
import com.example.newcanaryproject.ui.theme.greenColor
import java.io.File
import java.io.FileInputStream
import java.io.FileOutputStream
import java.io.IOException
 
class MainActivity : ComponentActivity() {
 
    var message = ""
    override fun onCreate(savedInstanceState: Bundle?) {
 
        super.onCreate(savedInstanceState)
        setContent {
            NewCanaryProjectTheme {
                // on below line we are specifying
                // background color for our application
                Surface(
                    // on below line we are specifying modifier and color for our app
                    modifier = Modifier.fillMaxSize(), color = MaterialTheme.colors.background
                ) {
 
                    // on the below line we are specifying
                    // the theme as the scaffold.
                    Scaffold(
 
                        // in scaffold we are specifying the top bar.
                        topBar = {
 
                            // inside top bar we are specifying
                            // background color.
                            TopAppBar(backgroundColor = greenColor,
 
                                // along with that we are
                                // specifying title for our top bar.
                                title = {
 
                                    // in the top bar we are specifying tile as a text
                                    Text(
                                        // on below line we are specifying
                                        // text to display in top app bar.
                                        text = "GFG",
 
                                        // on below line we are specifying
                                        // modifier to fill max width.
                                        modifier = Modifier.fillMaxWidth(),
 
                                        // on below line we are specifying
                                        // text alignment.
                                        textAlign = TextAlign.Center,
 
                                        // on below line we are specifying
                                        // color for our text.
                                        color = Color.White
                                    )
                                })
                        }) {
                        // on below line we are calling method to display UI
                        saveDataToExternalStorage(context = LocalContext.current, message)
                    }
                }
            }
        }
    }
}
 
@Composable
fun saveDataToExternalStorage(context: Context, msg: String) {
    // on below line creating a variable for message.
    val message = remember {
        mutableStateOf("")
    }
    val txtMsg = remember {
        mutableStateOf("")
    }
    val activity = context as Activity
 
    // on below line we are creating a column,
    Column(
        // on below line we are adding a modifier to it,
        modifier = Modifier
            .fillMaxSize()
            // on below line we are adding a padding.
            .padding(all = 30.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center,
    ) {
 
        // on below line we are adding a text for heading.
        Text(
            // on below line we are specifying text
            text = "External Storage in Android",
            // on below line we are specifying text color,
            // font size and font weight
            color = greenColor,
            textAlign = TextAlign.Center,
            fontSize = 20.sp,
            fontWeight = FontWeight.Bold
        )
 
        // on below line adding a spacer.
        Spacer(modifier = Modifier.height(10.dp))
        // on below line we are creating a text field for our message number.
        TextField(
            // on below line we are specifying value for our message text field.
            value = message.value,
            // on below line we are adding on value change for text field.
            onValueChange = { message.value = it },
            // on below line we are adding place holder as text as "Enter your email"
            placeholder = { Text(text = "Enter your message") },
            // on below line we are adding modifier to it
            // and adding padding to it and filling max width
            modifier = Modifier
                .padding(16.dp)
                .fillMaxWidth(),
            // on below line we are adding text style
            // specifying color and font size to it.
            textStyle = TextStyle(color = Color.Black, fontSize = 15.sp),
            // on below line we are adding single line to it.
            singleLine = true,
        )
 
        // on below line adding a spacer.
        Spacer(modifier = Modifier.height(10.dp))
 
        Row(
            modifier = Modifier
                .fillMaxWidth()
                .padding(all = 10.dp),
            horizontalArrangement = Arrangement.Center
        ) {
            // on below line adding a button.
            Button(
                onClick = {
 
                    // Requesting Permission to access External Storage
                    // Requesting Permission to access External Storage
                    ActivityCompat.requestPermissions(
                        activity, arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE), 23
                    )
 
                    // getExternalStoragePublicDirectory() represents root of external storage, we are using DOWNLOADS
                    // We can use following directories: MUSIC, PODCASTS, ALARMS, RINGTONES, NOTIFICATIONS, PICTURES, MOVIES
                    val folder: File =
                        Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
 
                    // Storing the data in file with name as geeksData.txt
                    val file = File(folder, "geeksData.txt")
                    writeTextData(file, message.value, context)
                    message.value = ""
                    // displaying a toast message
                    Toast.makeText(context, "Data saved publicly..", Toast.LENGTH_SHORT).show()
 
                },
                // on below line adding a modifier for our button.
                modifier = Modifier
                    .padding(5.dp)
                    .width(120.dp)
            ) {
                // on below line adding a text for our button.
                Text(text = "Save Publicly", textAlign = TextAlign.Center)
            }
            // on below line adding a spacer
            Spacer(modifier = Modifier.width(10.dp))
            // on below line creating a button
            Button(
                onClick = {
 
                    // Creating folder with name GeekForGeeks
                    val folder: File? = context.getExternalFilesDir("GeeksForGeeks")
 
                    // Creating file with name gfg.txt
 
                    // Creating file with name gfg.txt
                    val file = File(folder, "gfg.txt")
                    writeTextData(file, message.value, context)
 
                    message.value = ""
                    // displaying a toast message
                    Toast.makeText(context, "Data saved privately", Toast.LENGTH_SHORT).show()
 
                },
                // on below line adding a modifier for our button.
                modifier = Modifier
                    .padding(5.dp)
                    .width(120.dp)
            ) {
                // on below line adding a text for our button.
                Text(text = "Save Privately", textAlign = TextAlign.Center)
            }
        }
 
        // adding spacer on below line.
        Spacer(modifier = Modifier.height(100.dp))
 
        // on below line adding a text view to display our data.
        Text(
            // on below line we are specifying text
            text = "Data will appear below : \n" + txtMsg.value,
            // on below line we are specifying text color,
            // font size and font weight
            color = greenColor,
            textAlign = TextAlign.Center,
            fontSize = 20.sp,
            fontWeight = FontWeight.Bold
        )
 
        // on below line adding a Spacer.
        Spacer(modifier = Modifier.height(10.dp))
 
        Row(
            modifier = Modifier
                .fillMaxWidth()
                .fillMaxSize()
                .padding(all = 20.dp),
            horizontalArrangement = Arrangement.Center
        ) {
            // on below line adding a button.
            Button(
                onClick = {
                    // Accessing the saved data from the downloads folder
                    val folder =
                        Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
 
                    // geeksData represent the file data that is saved publicly
                    val file = File(folder, "geeksData.txt")
                    val data: String = getdata(file)
                    if (data != null && data != "") {
                        txtMsg.value = data
                    } else {
                        txtMsg.value = "No Data Found"
                    }
                },
                // on below line adding a modifier for our button.
                modifier = Modifier
                    .padding(5.dp)
                    .width(120.dp)
            ) {
                // on below line adding a text for our button.
                Text(text = "View\nPublic", textAlign = TextAlign.Center)
            }
            // on below line adding a spacer
            Spacer(modifier = Modifier.width(10.dp))
            // on below line creating a button
            Button(
                onClick = {
 
                    // GeeksForGeeks represent the folder name to access privately saved data
                    val folder: File? = context.getExternalFilesDir("GeeksForGeeks")
 
                    // gft.txt is the file that is saved privately
                    val file = File(folder, "gfg.txt")
                    val data = getdata(file)
                    if (data != null) {
                        txtMsg.value = data
                    } else {
                        txtMsg.value = "No Data Found"
                    }
                },
                // on below line adding a modifier for our button.
                modifier = Modifier
                    .padding(5.dp)
                    .width(120.dp)
            ) {
                // on below line adding a text for our button.
                Text(text = "View\nPrivate", textAlign = TextAlign.Center)
            }
        }
    }
}
 
// on below line creating get data method to get data from file.
private fun getdata(myfile: File): String {
    // on below line creating a variable for file input stream.
    var fileInputStream: FileInputStream? = null
    // on below line reading data from file and returning it.
    try {
        fileInputStream = FileInputStream(myfile)
        var i = -1
        val buffer = StringBuffer()
        while (fileInputStream.read().also { i = it } != -1) {
            buffer.append(i.toChar())
        }
        return buffer.toString()
    } catch (e: java.lang.Exception) {
        e.printStackTrace()
    } finally {
        if (fileInputStream != null) {
            try {
                fileInputStream.close()
            } catch (e: IOException) {
                e.printStackTrace()
            }
        }
    }
    return ""
}
 
// on below line creating a method to write data to txt file.
private fun writeTextData(file: File, data: String, context: Context) {
    var fileOutputStream: FileOutputStream? = null
    try {
        fileOutputStream = FileOutputStream(file)
        fileOutputStream.write(data.toByteArray())
    } catch (e: Exception) {
        e.printStackTrace()
    } finally {
        if (fileOutputStream != null) {
            try {
                fileOutputStream.close()
            } catch (e: IOException) {
                e.printStackTrace()
            }
        }
    }
}


Now run your application to see the output of it. 

Output:



Last Updated : 24 Jan, 2023
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads