What’s Android AIDL? How To Implement This?

This Image is AI-Generated

In the Android-based ecosystem, each application can be thought of as an isolated room. in each of these rooms, has its own components, attributes and processes. This of course makes the application run more secure and stable. Imagine if each application was not isolated, if one application had an error/crash, the other applications could be affected.

This Image is AI-Generated — Musicplayer Illustration

Apart from these mutually isolated applications, sometimes, in some cases, applications need to communicate with other applications. For example, a music player application whose buttons need to be controlled by a widget on the homescreen. This is when the concept of Inter-Process Communication (IPC) or Inter-Process Communication becomes crucial.

From many IPC mechanisms provided by Android, AIDL (Android Interface Definition Language) is the best and the most useful approach. Although it has a steeper learning curve, mastering AIDL will unlock the ability to design modular, high-performance, and extensible application systems. This guide will take you from the basic concepts of IPC to the step-by-step implementation of AIDL.

This Image is AI-Generated — AIDL Android Architecture

At First, you may confuse between AIDL and Android Service. So what’s difference?

Android Service is a component of Android that is used to run jobs in the background without relying on UI. The service is often used for tasks such as music playback, location tracking, data synchronization, or processes that need to continue even if the user moves to another screen

AIDL (Android Interface Definition Language) is not a replacement for Service, but rather an inter-process communication mechanism (IPC). AIDL is used when a Service needs to be accessed by another application or run on a different process, so communication cannot be made directly through a regular Java/Kotlin object. With AIDL, developers define interface contracts that can be called securely across processes, making them suitable solutions for SDKs, system applications, or services shared with other applications.

Android Service Without AIDL

For example music player app:

class MusicService : Service() {

fun playMusic() {
        // play music
    }
    override fun onBind(intent: Intent?): IBinder {
        return LocalBinder()
    }
    inner class LocalBinder : Binder() {
        fun getService(): MusicService = this@MusicService
    }
}

Activity can call service directly:

musicService.playMusic()

Because Activity and Service in same process, so AIDL is not necessary.

Android Service With AIDL

For example you make payment app or chatbot that provides service for other apps.

ICalculator.aidl

interface ICalculator {
    int add(int a, int b);
}

Service:

class CalculatorService : Service() {

private val binder = object : ICalculator.Stub() {
        override fun add(a: Int, b: Int): Int {
            return a + b
        }
    }
    override fun onBind(intent: Intent?): IBinder {
        return binder
    }
}

Other apps can call:

calculatorService.add(10, 20)

Although service run in different process.

Okay, enough for the theory.. then how to Implement AIDL?

Step-by-Step Implementation

1. Create the AIDL Interface

In Android Studio:

Create the directory structure: src/main/aidl/com/example/myapp (if it doesn’t exist).

Right-click the package → New → AIDL → AIDL File → name it IMyAidlInterface.aidl.

MyAidlInterface.aidl

// IMyAidlInterface.aidl
package samseptiano.example.sampleaidl;

interface IMyAidlInterface {
    int add(int a, int b);
    String getMessage(String name);
    oneway void performLongOperation(int value);
}

2. Implement the Service

MyAidlService.kt

package samseptiano.example.sampleaidl

import android.app.Service
import android.content.Intent
import android.os.IBinder
import android.util.Log
class MyAidlService : Service() {
    private val binder = object : IMyAidlInterface.Stub() {
        override fun add(a: Int, b: Int): Int {
            Log.d("MyAidlService", "add: $a + $b")
            return a + b
        }
        override fun getMessage(name: String?): String {
            return "Hello from AIDL Service, ${name ?: "Guest"}!"
        }
        override fun performLongOperation(value: Int) {
            Log.d("MyAidlService", "Long operation started with: $value")
            Thread.sleep(1500) // Simulate work
            Log.d("MyAidlService", "Long operation completed")
        }
    }
    override fun onBind(intent: Intent?): IBinder = binder
}

3. Register AIDL Service in AndroidManifest.xml

<service
    android:name=".MyAidlService"
    android:exported="true"
    android:process=":remote" />  <!-- Optional: run in separate process -->

4. AidlDemoScreen

Create composable AidlDemoScreen.kt

package samseptiano.example.sampleaidl.screen

import androidx.compose.foundation.layout.*
import androidx.compose.material3.*
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
@Composable
fun AidlDemoScreen(
    isBound: Boolean,
    onAddClick: (Int, Int) -> Int,
    onGetMessageClick: (String) -> String,
    onLongOperationClick: () -> Unit
) {
    var result by remember { mutableStateOf("") }
    var inputA by remember { mutableStateOf("5") }
    var inputB by remember { mutableStateOf("7") }
    var name by remember { mutableStateOf("User") }
    Column(
        modifier = Modifier
            .fillMaxSize()
            .padding(16.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.spacedBy(16.dp)
    ) {
        Text(
            text = "AIDL Service Demo",
            style = MaterialTheme.typography.headlineMedium
        )
        Text(
            text = if (isBound) "Service Connected" else "Connecting to service...",
            color = if (isBound) MaterialTheme.colorScheme.primary else MaterialTheme.colorScheme.error
        )
        // Addition
        Card(modifier = Modifier.fillMaxWidth()) {
            Column(modifier = Modifier.padding(16.dp)) {
                Text("Addition", style = MaterialTheme.typography.titleMedium)
                Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
                    OutlinedTextField(
                        value = inputA,
                        onValueChange = { inputA = it },
                        label = { Text("Number A") },
                        modifier = Modifier.weight(1f)
                    )
                    OutlinedTextField(
                        value = inputB,
                        onValueChange = { inputB = it },
                        label = { Text("Number B") },
                        modifier = Modifier.weight(1f)
                    )
                }
                Button(
                    onClick = {
                        val sum = onAddClick(inputA.toIntOrNull() ?: 0, inputB.toIntOrNull() ?: 0)
                        result = "Sum: $sum"
                    },
                    modifier = Modifier.fillMaxWidth()
                ) {
                    Text("Calculate Sum")
                }
            }
        }
        // Message
        Card(modifier = Modifier.fillMaxWidth()) {
            Column(modifier = Modifier.padding(16.dp)) {
                Text("Get Message", style = MaterialTheme.typography.titleMedium)
                OutlinedTextField(
                    value = name,
                    onValueChange = { name = it },
                    label = { Text("Your Name") },
                    modifier = Modifier.fillMaxWidth()
                )
                Button(
                    onClick = {
                        result = onGetMessageClick(name)
                    },
                    modifier = Modifier.fillMaxWidth()
                ) {
                    Text("Get Greeting")
                }
            }
        }
        // Long Operation
        Button(
            onClick = {
                onLongOperationClick()
                result = "Long operation started (check Logcat)"
            },
            modifier = Modifier.fillMaxWidth()
        ) {
            Text("Start Long Operation (One-way)")
        }
        Spacer(modifier = Modifier.height(8.dp))
        // Result Display
        if (result.isNotEmpty()) {
            Card(
                colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.surfaceVariant),
                modifier = Modifier.fillMaxWidth()
            ) {
                Text(
                    text = result,
                    modifier = Modifier.padding(16.dp),
                    style = MaterialTheme.typography.bodyLarge
                )
            }
        }
    }
}

5. MainActivity

Call AidlDemoScreen.kt to our MainActivity.ktand don’t forget to bind our AIDL

package samseptiano.example.sampleaidl

import android.content.ComponentName
import android.content.Context
import android.content.Intent
import android.content.ServiceConnection
import android.os.Bundle
import android.os.IBinder
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.runtime.*
import samseptiano.example.sampleaidl.screen.AidlDemoScreen
class MainActivity : ComponentActivity() {
    private var myService: IMyAidlInterface? = null
    private var isBound by mutableStateOf(false)
    private val connection = object : ServiceConnection {
        override fun onServiceConnected(name: ComponentName?, service: IBinder?) {
            myService = IMyAidlInterface.Stub.asInterface(service)
            isBound = true
        }
        override fun onServiceDisconnected(name: ComponentName?) {
            myService = null
            isBound = false
        }
    }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // Bind to service
        val intent = Intent(this, MyAidlService::class.java)
        bindService(intent, connection, Context.BIND_AUTO_CREATE)
        setContent {
            AidlDemoScreen(
                isBound = isBound,
                onAddClick = { a, b ->
                    myService?.add(a, b) ?: 0
                },
                onGetMessageClick = { name ->
                    myService?.getMessage(name) ?: "Service not connected"
                },
                onLongOperationClick = {
                    myService?.performLongOperation(42)
                }
            )
        }
    }
    override fun onDestroy() {
        if (isBound) {
            unbindService(connection)
            isBound = false
        }
        super.onDestroy()
    }
}

6. Build Configuration (app/build.gradle)

Make sure AIDL is enabled in app/build.gradle (usually default in modern projects):

android {
    ...
    buildFeatures {
        compose = true
        aidl = true /*set true*/
    }
}

Now Compile our project and Voilaaa it will run perfectly!!

sample demo

For sample code, you can visit this *link *:)

So, When to use AIDL and Android Service?

Use Android Service when you want to do things in the background of your Android application you should use an Android Service. This is useful for things like playing music tracking where you are syncing your data or doing things that take a time.

You should use AIDL, when you need to access a Service from applications or, from different parts of your system. AIDL helps different applications talk to each other which is called Inter-Process Communication. It lets other applications use a Service as if it was their own.