# Chat

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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.

While in a session, users can send chat messages to other users in the session.

The following two main components within the SDK will help you implement in-session message features:

-   The `onChatNewMessageNotify` callback is triggered when a new message is sent or received. This callback confirms the delivery of the message.
-   An instance of `ZoomVideoSDKChatHelper` provides methods that can be used to send and receive messages in a session running on your app.

> **Note:** Common chat implementations in Android utilize `RecyclerViews` to display messages. This documentation will only cover how to obtain information from the `ZoomVideoSDK` Chat API. If you would like to use this API with `RecyclerViews`, see [RecyclerViews in Android](https://developer.android.com/guide/topics/ui/layout/recyclerview).

## Send chat messages

There are two different forms of chat in a session: **public** and **private**. A private message is sent to a specific user in the session and a public message is sent to all users present in the session.

Before sending a private message to a specific user, you must verify that private chat is enabled in your session and obtain the user you would like to send the message to.

1. Obtain an instance of the **ZoomVideoSDKChatHelper** object.

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

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

2. Check if chat is disabled prior to setting up chat-related components.

    ```kotlin
    chatHelper.isChatDisabled
    ```

    ```java
    chatHelper.isChatDisabled();
    ```

3. Send a private chat message

    ```kotlin
    if (chatHelper.isPrivateChatDisabled) {
        // You cannot send user-specific messages
    } else {
        chatHelper.sendChatToUser(user, "This is a private message")
    }
    ```

    ```java
    if (chatHelper.isPrivateChatDisabled()) {
        // You cannot send user-specific messages
    } else {
        chatHelper.sendChatToUser(user, "This is a private message");
    }
    ```

4. Send a public chat message

    ```kotlin
    chatHelper.sendChatToAll("This is a public message")
    ```

    ```java
    chatHelper.sendChatToAll("This is a public message");
    ```

## Receive chat messages

Whenever a chat message is received, the most important pieces of data to make note of are the **sender** and the **content** of the message.

You can use this information to display the sender information such as the user name and content of the message to the message recipient(s) in your UI.

1. Get notified when a chat message is received

    ```kotlin
    override fun onChatNewMessageNotify(chatHelper: ZoomVideoSDKChatHelper?, messageItem: ZoomVideoSDKChatMessage) {
        val content = messageItem.content
        val sender = messageItem.senderUser
        val senderName = sender.userName
    }
    ```

    ```java
    @Override
    public void onChatNewMessageNotify(ZoomVideoSDKChatHelper chatHelper, ZoomVideoSDKChatMessage messageItem) {
        String content = messageItem.getContent();
        ZoomVideoSDKUser sender = messageItem.getSenderUser();
        String senderName = sender.getUserName();
    }
    ```

For more information on how to use the `ZoomVideoSDKUserInfo` object, see [Sessions](/docs/video-sdk/android/sessions).

## More details

You can find out more details about chats using `ZoomVideoSDKChatMessage`:

```kotlin
messageItem.isChatToAll // Returns false for private messages
messageItem.isSelfSend // Returns true if current user sent the message
messageItem.timeStamp // The time at which the message was sent
messageItem.receiverUser // The recipient for a private message
```

```java
messageItem.isChatToAll(); // Returns false for private messages
messageItem.isSelfSend(); // Returns true if current user sent the message
messageItem.getTimeStamp(); // The time at which the message was sent
messageItem.getReceiverUser(); // The recipient for a private message
```

## Callbacks

The following is an example of a chat callback.

### Get notified when a message is posted

```kotlin
override fun onChatNewMessageNotify(chatHelper: ZoomVideoSDKChatHelper?, messageItem: ZoomVideoSDKChatMessage) {
    val content = messageItem.content
    val sender = messageItem.senderUser
}
```

```java
@Override
public void onChatNewMessageNotify(ZoomVideoSDKChatHelper chatHelper, ZoomVideoSDKChatMessage messageItem) {
    String content = messageItem.getContent();
    ZoomVideoSDKUser sender = messageItem.getSenderUser();
}
```

## Send files in chat

Users can transfer files in chat during the session.

> Zoom deletes files sent via in-session chat when the session ends.

Enable [send files via in-session chat](/docs/build/account/#in-session-advanced) in your Video SDK account portal settings and configure the following settings.

-   **Only allow specified file types** - Select to allow only specific file types and enter the file extensions in the text box, separated by commas.
-   **Maximum file size** - Select to limit the file size to 2048 MB.

Check if the file transfer feature is enabled.

```kotlin
if (ZoomVideoSDK.getInstance().session.isFileTransferEnable) {
    // File Transfer is enabled.
}
```

Get the list of allowed file types that you can transfer.

```kotlin
ZoomVideoSDK.getInstance().session.transferFileTypeWhiteList
```

Get the maximum file size to transfer.

```kotlin
ZoomVideoSDK.getInstance().session.maxTransferFileSize
```

Send files to all users in the current session.

```kotlin
val error = ZoomVideoSDK.getInstance().session.transferFile("filePath")
if (error == 0) {
    // Transfer successfully
} else {
    // Failed to transfer
}
```

Send files to a certain user in the session.

```kotlin
// Get the user you want to send file to
val userToReceiveFile: ZoomVideoSDKUser
val error = userToReceiveFile.transferFile("filePath")
if (error == 0) {
    // Transfer successfully
} else {
    // Failed to transfer
}
```

Cancel sending files.

```kotlin
// onSendFileStatus under ZoomVideoSDKDelegate
if (file != null && status != null && status == ZoomVideoSDKFileTransferStatus.FileTransferState_TransferDone) {
    val error = file.cancelSend()
}
```

Start receiving files.

```kotlin
// onReceiveFileStatus under ZoomVideoSDKDelegate
override fun onReceiveFileStatus(
    file: ZoomVideoSDKReceiveFile?,
    status: ZoomVideoSDKFileTransferStatus?
) {
    if (file != null && status != null) {
        val error = file.startReceive("filePath")
    }
}
```

Cancel receiving files.

```kotlin
// onReceiveFileStatus under ZoomVideoSDKDelegate
override fun onReceiveFileStatus(
    file: ZoomVideoSDKReceiveFile?,
    status: ZoomVideoSDKFileTransferStatus?
) {
    if (file != null && status != null) {
        val error = file.cancelReceive()
    }
}
```

### File transfer callbacks

Be sure that you [listen for callback events](/docs/video-sdk/android/integrate/#listen-for-callback-events) to receive file transfer callbacks.

Get notified when you transfer a file.

```kotlin
override fun onSendFileStatus(
    file: ZoomVideoSDKSendFile?,
    status: ZoomVideoSDKFileTransferStatus?
) {

}
```

Get notified when you receive a file from other users.

```kotlin
 override fun onReceiveFileStatus(
    file: ZoomVideoSDKReceiveFile?,
    status: ZoomVideoSDKFileTransferStatus?
) {

}
```