Custom Text Formatter

Extend CometChatTextFormatter to build custom inline text patterns with tracking characters and suggestion lists.

AI Agent Component Spec

Field	Value
Package	com.cometchat:chat-uikit-android
Key class	CometChatTextFormatter (abstract base class for custom formatters)
Required setup	CometChatUIKit.init() then CometChatUIKit.login("UID")
Purpose	Extend to create custom inline text patterns with tracking characters, suggestion lists, and span formatting
Features	Tracking character activation, suggestion list, span formatting per context (composer, bubbles, conversations), pre-send hooks
Sample app	GitHub
Related	Mentions Formatter | ShortCut Formatter | All Guides

CometChatTextFormatter is an abstract class for formatting text in the message composer and message bubbles. Extend it to build custom formatters — hashtags, shortcuts, or any pattern triggered by a tracking character.

Capability	Description
Tracking character	Activates the formatter when the user types a specific character (e.g., #, !)
Suggestion list	Populates a dropdown of SuggestionItem objects as the user types
Span formatting	Applies SpannableStringBuilder spans per context: composer, left/right bubbles, conversations
Pre-send hook	handlePreMessageSend lets you modify the message before it’s sent
Component integration	Plugs into any component via setTextFormatters()

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Steps

1. Create a class extending CometChatTextFormatter

Pass your tracking character to the superclass constructor.

Kotlin

class HashTagFormatter : CometChatTextFormatter('#') {
    private val suggestions: MutableList<SuggestionItem> = ArrayList()
}

Java

public class HashTagFormatter extends CometChatTextFormatter {
    private List<SuggestionItem> suggestions = new ArrayList<>();

    public HashTagFormatter() {
        super('#');
    }
}

2. Override the search method

Called when the user types after the tracking character. Match input against your data and update the suggestion list.

Kotlin

override fun search(context: Context, queryString: String?) {
    suggestions.clear()
    val query = "#${queryString ?: ""}"
    // Match against your hashtag data source
    val matchingTags = getMatchingTags(query)
    for (tag in matchingTags) {
        val item = SuggestionItem("", tag, null, null, tag, null, null)
        item.isHideLeadingIcon = true
        suggestions.add(item)
    }
    setSuggestionItemList(suggestions)
}

Java

@Override
public void search(@NonNull Context context, @Nullable String queryString) {
    suggestions.clear();
    String query = "#" + (queryString != null ? queryString : "");
    // Match against your hashtag data source
    List<String> matchingTags = getMatchingTags(query);
    for (String tag : matchingTags) {
        SuggestionItem item = new SuggestionItem("", tag, null, null, tag, null, null);
        item.setHideLeadingIcon(true);
        suggestions.add(item);
    }
    setSuggestionItemList(suggestions);
}

3. Override onScrollToBottom

Required by the base class. Implement pagination logic or leave empty.

Kotlin

override fun onScrollToBottom() {
    // Load more suggestions if needed
}

Java

@Override
public void onScrollToBottom() {
    // Load more suggestions if needed
}

4. Override span formatting methods (optional)

Customize how matched text renders in different contexts using SpannableStringBuilder.

Kotlin

override fun prepareLeftMessageBubbleSpan(
    context: Context, baseMessage: BaseMessage, spannable: SpannableStringBuilder
): SpannableStringBuilder? {
    // Apply custom spans for incoming message bubbles
    return applyHashTagSpans(spannable, Color.parseColor("#5dff05"))
}

override fun prepareRightMessageBubbleSpan(
    context: Context, baseMessage: BaseMessage, spannable: SpannableStringBuilder
): SpannableStringBuilder? {
    // Apply custom spans for outgoing message bubbles
    return applyHashTagSpans(spannable, Color.parseColor("#30b3ff"))
}

Java

@Override
public SpannableStringBuilder prepareLeftMessageBubbleSpan(
    @NonNull Context context, @NonNull BaseMessage baseMessage, SpannableStringBuilder spannable) {
    return applyHashTagSpans(spannable, Color.parseColor("#5dff05"));
}

@Override
public SpannableStringBuilder prepareRightMessageBubbleSpan(
    @NonNull Context context, @NonNull BaseMessage baseMessage, SpannableStringBuilder spannable) {
    return applyHashTagSpans(spannable, Color.parseColor("#30b3ff"));
}

5. Integrate with a component

Kotlin

val textFormatters = CometChatUIKit.getDataSource().getTextFormatters(this, messageComposer.additionParameter)
textFormatters.add(HashTagFormatter())
messageComposer.setTextFormatters(textFormatters)

Java

List<CometChatTextFormatter> textFormatters = CometChatUIKit.getDataSource().getTextFormatters(this, messageComposer.getAdditionParameter());
textFormatters.add(new HashTagFormatter());
messageComposer.setTextFormatters(textFormatters);

Pass the same list to CometChatMessageList and CometChatConversations via their setTextFormatters() methods to apply formatting across all contexts.

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Methods Reference

Method	Description
search(Context, String)	Abstract — called when user types after the tracking character. Update the suggestion list here.
onScrollToBottom()	Abstract — called when the suggestion list scrolls to the bottom. Implement pagination or leave empty.
onItemClick(Context, SuggestionItem, User, Group)	Called when a suggestion item is selected. Override to customize insertion behavior.
handlePreMessageSend(Context, BaseMessage)	Called before a message is sent. Override to modify the message (e.g., add metadata).
prepareLeftMessageBubbleSpan(Context, BaseMessage, SpannableStringBuilder)	Override to format text in incoming message bubbles.
prepareRightMessageBubbleSpan(Context, BaseMessage, SpannableStringBuilder)	Override to format text in outgoing message bubbles.
prepareComposerSpan(Context, BaseMessage, SpannableStringBuilder)	Override to format text in the message composer.
prepareConversationSpan(Context, BaseMessage, SpannableStringBuilder)	Override to format text in the conversations list preview.
setSuggestionItemList(List<SuggestionItem>)	Updates the suggestion dropdown with new items.
setDisableSuggestions(boolean)	Disables the suggestion dropdown entirely. (protected — accessible from subclasses only.)
setInfoText(String)	Sets informational text displayed above the suggestion list.
setInfoVisibility(boolean)	Toggles visibility of the info text.
setShowLoadingIndicator(boolean)	Shows/hides a loading spinner in the suggestion dropdown.
getTrackingCharacter()	Returns the tracking character passed to the constructor.

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Next Steps

Mentions Formatter

Built-in @mention formatting with styled tokens

ShortCut Formatter

Shortcut text expansion via the message-shortcuts extension

All Guides

Browse all feature and formatter guides

Sample App

Full working sample application on GitHub