# Core features

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The Video SDK for Android provides in-session text chat: users can send public and private messages to everyone or to a specific user, and your app receives a callback as each message arrives. Use the `ZoomVideoSDKChatHelper` to send messages and listen for `onChatNewMessageNotify` on your `ZoomVideoSDKDelegate` to receive them.

To transfer files through chat, see [Send files in chat](/docs/video-sdk/android/chat/send-files-in-chat/). To read message metadata, delete messages, or apply host chat privileges, see [Manage chat messages](/docs/video-sdk/android/chat/chat-message-details/).

Chat is is designed to support in-session text communication. Zoom truncates messages exceeding a binary size of 10,000 bytes. As a best practice, we recommend a limit of 1000 characters per message.

> **Note**
>
> Common chat implementations in Android use `RecyclerView` to display messages. The following sections focus on the SDK chat API only. See [RecyclerView in Android](https://developer.android.com/guide/topics/ui/layout/recyclerview) for the UI side.

## Get the chat helper

To send messages or change privileges, grab the `ZoomVideoSDKChatHelper` from the SDK singleton. Every chat call hangs off it.

```kotlin
val chatHelper = ZoomVideoSDK.getInstance().chatHelper
```

```java
ZoomVideoSDKChatHelper chatHelper = ZoomVideoSDK.getInstance().getChatHelper();
```

## Send a public message

Before exposing a chat composer in your UI, check that chat is enabled. The host may have disabled it for the session through [chat privileges](/docs/video-sdk/android/chat/chat-message-details/#host-control-chat-privileges).

```kotlin
if (chatHelper.isChatDisabled) {
    // Chat is disabled for this session — hide your composer.
    return
}

val result = chatHelper.sendChatToAll("This is a public message")
if (result != ZoomVideoSDKErrors.Errors_Success) {
    // Surface the error to the user.
}
```

```java
if (chatHelper.isChatDisabled()) {
    // Chat is disabled for this session — hide your composer.
    return;
}

int result = chatHelper.sendChatToAll("This is a public message");
if (result != ZoomVideoSDKErrors.Errors_Success) {
    // Surface the error to the user.
}
```

`sendChatToAll` returns `ZoomVideoSDKErrors.Errors_Success` (value `0`) when the send is accepted by the SDK; any other value is an error code from [`ZoomVideoSDKErrors`](https://marketplacefront.zoom.us/sdk/custom/android/us/zoom/sdk/ZoomVideoSDKErrors.html).

## Send a private message

Private messages are also a chat privilege the host can disable, separately from public chat. Check `isPrivateChatDisabled` before exposing a "send to user" UI.

```kotlin
if (chatHelper.isPrivateChatDisabled) {
    // The host has disabled private chat.
    return
}

val result = chatHelper.sendChatToUser(user, "This is a private message")
if (result != ZoomVideoSDKErrors.Errors_Success) {
    // Surface the error to the user.
}
```

```java
if (chatHelper.isPrivateChatDisabled()) {
    // The host has disabled private chat.
    return;
}

int result = chatHelper.sendChatToUser(user, "This is a private message");
if (result != ZoomVideoSDKErrors.Errors_Success) {
    // Surface the error to the user.
}
```

## Receive incoming messages

Implement `onChatNewMessageNotify` on your `ZoomVideoSDKDelegate`. The callback fires for both messages you receive _and_ messages you send. Check `isSelfSend` if you want to distinguish (see [Manage chat messages](/docs/video-sdk/android/chat/chat-message-details/) for the full set of message accessors).

```kotlin
override fun onChatNewMessageNotify(
    chatHelper: ZoomVideoSDKChatHelper?,
    messageItem: ZoomVideoSDKChatMessage
) {
    val content = messageItem.content
    val sender = messageItem.senderUser
    // Add the message to your RecyclerView adapter.
}
```

```java
@Override
public void onChatNewMessageNotify(
    ZoomVideoSDKChatHelper chatHelper,
    ZoomVideoSDKChatMessage messageItem
) {
    String content = messageItem.getContent();
    ZoomVideoSDKUser sender = messageItem.getSenderUser();
    // Add the message to your RecyclerView adapter.
}
```

For everything else you can read off a `ZoomVideoSDKChatMessage` (timestamps, recipients, message ID, public-vs-private flag), see [Manage chat messages](/docs/video-sdk/android/chat/chat-message-details/).