---
description: API reference for RtkJoinButton component (Android Library)
title: RtkJoinButton
image: https://developers.cloudflare.com/og-docs.png
---

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# RtkJoinButton

Last updated Aug 25, 2026|Copy as Markdown|[View as Markdown](https://4f1c5cd2.previews.developers.cloudflare.com/realtime/realtimekit/ui-kit/api-reference/android/join-button/index.md)|[Agent setup](https://4f1c5cd2.previews.developers.cloudflare.com/agent-setup/)

A button that performs the room join operation. Displays "Join" by default and changes to "Joining..." during the join process. Automatically disables after a successful join.

## Methods

| Method   | Parameters                                                | Description                                                                                                                                                                                                                                                     |
| -------- | --------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| activate | meeting: RealtimeKitClient, localUserNameField: EditText? | Bind the button to the meeting state. Pass an optional EditText reference to validate the display name before joining — if the user has canEditDisplayName permission and the field is blank, the button shows a "Please enter name" toast and blocks the join. |

## Usage Examples

### Basic Usage

```xml
<com.cloudflare.realtimekit.ui.view.RtkJoinButton
    android:id="@+id/rtk_join_button"
    android:layout_width="wrap_content"
    android:layout_height="48dp"
    app:rtk_btn_variant="primary" />
```

### With Methods

```kotlin
val joinButton = findViewById<RtkJoinButton>(R.id.rtk_join_button)
val nameField = findViewById<EditText>(R.id.name_field)
joinButton.activate(meeting, nameField)
```

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