Android Jetpack Compose Internal Storage

Many times in the android application we have to save the data from our android application within the device storage. For storing the data we can store it in shared preferences, internal as well as external storage. In this article, we will take a look at How to save data to Internal storage in Android using Jetpack Compose.

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: 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.app.Activity
import android.content.*
import android.os.Bundle
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 com.example.newcanaryproject.ui.theme.NewCanaryProjectTheme
import com.example.newcanaryproject.ui.theme.greenColor
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
                                    // title 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 = "Internal 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 ar adding single line to it.
            singleLine = true,
        )

        // on below line adding a spacer.
        Spacer(modifier = Modifier.height(10.dp))


        // on below line adding a button.
        Button(
            onClick = {
                // on below line we are saving data to internal storage
                try {
                    val fos: FileOutputStream =
                        context.openFileOutput("demoFile.txt", Context.MODE_PRIVATE)
                    fos.write(message.value.toByteArray())
                    fos.flush()
                    fos.close()
                } catch (e: IOException) {
                    e.printStackTrace()
                }
                message.value = ""
                Toast.makeText(context, "Data saved successfully..", Toast.LENGTH_SHORT).show()

            },
            // on below line adding a modifier for our button.
            modifier = Modifier
                .padding(5.dp)
                .fillMaxWidth()
        ) {
            // on below line adding a text for our button.
            Text(text = "Write Data to Internal Storage", textAlign = TextAlign.Center)
        }
        // on below line adding a spacer
        Spacer(modifier = Modifier.width(10.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
        )
        // adding spacer on below line.
        Spacer(modifier = Modifier.height(20.dp))
        // on below line creating a button
        Button(
            onClick = {
                // on below line we are reading the
                // data which we stored in our file.
                try {
                    val fin: FileInputStream = context.openFileInput("demoFile.txt")
                    var a: Int
                    val temp = StringBuilder()
                    while (fin.read().also { a = it } != -1) {
                        temp.append(a.toChar())
                    }

                    txtMsg.value = temp.toString()
                    fin.close()
                } catch (e: IOException) {
                    e.printStackTrace()
                }

            },
            // on below line adding a
            // modifier for our button.
            modifier = Modifier
                .padding(5.dp)
                .fillMaxWidth()
        ) {
            // on below line adding a text for our button.
            Text(text = "Read Data from Internal Storage", textAlign = TextAlign.Center)
        }
    }
}

Now run your application to see the output of it. 

Output: