Label

Label is the most widely used display widget: it shows read-only text, with automatic line wrapping (word-wrap), multiple lines (explicit via \n or automatic) and optional icons on the left and/or right. It does not respond to touch — for actions use Button; for editable text use TextField/TextArea.

Rendering is delegated to the active Design: the Label only computes coordinates in onLayout() and exposes public fields that the Design consumes (font, colors and borders come from the LabelStyle).

🟢 · Package: dev.crossfly.ui · Extends: Component · Style: LabelStyle

When to use

• Titles, subtitles, captions and read-only values.
• Text with an informative icon on the left or right.
• Blocks of text that need to wrap across multiple lines.

When NOT to use

• Editable text → use TextField / TextArea.
• Touchable / clickable element → use Button (the Label does not respond to touch).

Appearance

The text is rendered within the internal area (after ingap), aligned horizontally and vertically according to LabelStyle.textAlignH/textAlignV. The left icon sits flush against the internal left edge; the right icon against the internal right edge; the text occupies the space between them.

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Complete example (copy, paste and run)

package com.exemplo;

import dev.crossfly.ui.*;
import dev.crossfly.ui.layout.*;

/** Runnable main screen. Point the launcher (classname) and run: gradlew :lwjgl3:run */
public class MainWindow extends Window
{
   @Override
   public void onShow() throws Exception
   {
      super.onShow();
      setLayout(new VerticalLayout());

      // Read-only Label that will be updated by the button
      Label saida = new Label("Toque no botão abaixo");
      add(LAY_AUTO, saida);

      // Button that mutates the Label's text (Label.setText is fluent and returns Label)
      Button ola = new Button("Dizer olá").onAction(c -> saida.setText("Olá, mundo!"));
      add(LAY_AUTO, ola);
   }
}

The snippets below show only the core (what goes inside onShow()). To run them, place them in the MainWindow skeleton above.

Basic usage

Label hello = new Label("Olá, mundo!");
container.add(LAY_AUTO, hello);

Constructors

Properties and customization

setText(String) returns Label (for fluency), not void — that is why Label does not declare implements TextComponent, despite exposing setText/text.

Callbacks and events

None. Label is non-interactive — it fires neither onAction nor touch events.

States

No interaction states (there is no pressed/focused). The visual changes only with the applied style or via setEnabled(false) (disabled appearance, according to the Design).

Left icon and subtitle without background

// Label with an icon on the left (Material "info")
Label info = new Label("Informação")
   .leftIcon(new MaterialIcon(""));
container.add(LAY_AUTO, info);

// Left-aligned subtitle, no background/border
Label sub = new Label("Lista:").style(
   Styles.theme().label(LabelRole.SUBTITLE)
      .backColor(0)
      .borderColor(0)
      .textAlign(Position.START, Position.CENTER));
container.add(LAY_AUTO, sub);

Multiline (word-wrap + explicit \n)

// Explicit breaks
Label endereco = new Label("Rua das Flores, 123\nCentro\n01000-000");

// Automatic word-wrap: give the Label a width (LAY_FILL) for the break to occur
Label paragrafo = new Label(
   "Este texto longo quebra automaticamente em várias linhas quando "
 + "a largura disponível é menor que a largura do texto.");
container.add(LAY_FILL, paragrafo);

Best practices

• For word-wrap, make sure the layout gives the Label a width (e.g. add(LAY_FILL, label) in a VerticalLayout). Without a known width, only the explicit \n are counted toward the height.
• Use theme roles (LabelRole.TITLE/SUBTITLE/…) instead of hard-coding font/color.

Common mistakes

• Expecting word-wrap without a defined width: if the width is 0/unknown during the height calculation, only the explicit \n breaks count. Give the Label a width.
• Confusing setText with the TextComponent.setText contract: here setText returns Label, not void; the Label does not implement TextComponent.

See also

• Area guide: ui/ · Recipes: cookbook/
• Concept (“everything is a Component”): concepts/
• Related components: Button · TextField · ImageView