# Android Development

IC4J Agent library can be also used for development of native Android application written in Java or Kotlin. Use [Android Studio](https://developer.android.com/studio) to start a new Android application or add support for the Internet Computer to your existing application.

To add required IC4J libraries to your Android project open **gradle.build** file and add dependencies:

```
    implementation 'commons-codec:commons-codec:1.17.0'
    implementation 'org.ic4j:ic4j-candid:0.8.0'
    implementation('org.ic4j:ic4j-agent:0.8.0') {
        exclude group: 'org.apache.httpcomponents.client5', module: 'httpclient5'
    }
    implementation 'org.slf4j:slf4j-api:2.0.13'
```

Android application preferably uses [OkHttp HTTP](/reference/api-reference/replicatransport.md#okhttp-client-transport-implementation) client so Apache HTTP 5 library can be excluded.

To be able to connect to the Internet Computer Canister set **uses-permission** in project AndroidManifest.xml descriptor.

```xml
<uses-permission android:name="android.permission.INTERNET"/>
```

## Use IC4J with Kotlin

[AndroidHelloWord](https://github.com/ic4j/samples/tree/master/AndroidHelloWorld) sample application demonstrates use or [QueryBuilder](/reference/api-reference/querybuilder-and-updatebuilder.md#querybuilder) and [UpdateBuilder](/reference/api-reference/querybuilder-and-updatebuilder.md#updatebuilder) in Kotlin Android project. Project properties **ic.location** and **ic.canister** are stored in [strings.xml](https://github.com/ic4j/samples/blob/master/AndroidHelloWorld/app/src/main/res/values/strings.xml) file.

[MainActivity.kt](https://github.com/ic4j/samples/blob/master/AndroidHelloWorld/app/src/main/java/org/ic4j/samples/android/helloworld/MainActivity.kt) has a simple code for QUERY and UPDATE invocation of the Canister code [main.mo](https://github.com/ic4j/samples/blob/master/AndroidHelloWorld/main.mo).

{% code title="main.mo" %}

```javascript
actor {
    stable var name = "Me";

    public func greet(value : Text) : async Text {
        name := value;
        return "Hello, " # name # "!";
    };

    public shared query func peek() : async Text {
        return name;
    };
};
```

{% endcode %}

Using [QueryBuilder](/reference/api-reference/querybuilder-and-updatebuilder.md#querybuilder) in Kotlin.

{% code title="MainActivity.kt" %}

```kotlin
val url: String = getString(R.string.url)
val canister: String = getString(R.string.canister)

val identity: Identity = AnonymousIdentity()
val transport: ReplicaTransport =
                ReplicaOkHttpTransport.create(url)

val agent: Agent = AgentBuilder().identity(identity).transport(transport).build()
val buf = IDLArgs.create(ArrayList<IDLValue>()).toBytes()
val principal = Principal.fromString(canister);

val response = QueryBuilder.create(
                        agent,
                        principal,
                        "peek"
           ).arg(buf).call()

val output = response.get()
val outArgs = IDLArgs.fromBytes(output)
name = outArgs.args[0].getValue<String>()
```

{% endcode %}

Using [UpdateBuilder](/reference/api-reference/querybuilder-and-updatebuilder.md#updatebuilder) in Kotlin.

{% code title="MainActivity.kt" %}

```kotlin
val url : String = getString(R.string.url)
val canister : String = getString(R.string.canister)

val identity : Identity = AnonymousIdentity()
val transport: ReplicaTransport =
                ReplicaOkHttpTransport.create(url)
val agent: Agent = AgentBuilder().identity(identity).transport(transport).build()

val arg : IDLValue = IDLValue.create(message)
var args : ArrayList<IDLValue> = ArrayList<IDLValue>()
args.add(arg)
val buf = IDLArgs.create(args).toBytes()

val response = UpdateBuilder.create(
                        agent,
                        Principal.fromString(canister),
                        "greet"
            ).arg(buf).callAndWait(Waiter.create(60, 5))

val output = response.get()
val outArgs = IDLArgs.fromBytes(output)
val outputMessage = outArgs.args[0].getValue<String>()
```

{% endcode %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.ic4j.com/reference/api-reference/android-development.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.