} element that contains a * header that is always visible, main content that * can be scrolled if necessary, and optional side and footer * contents that are only rendered if available. */ public class BodyContents extends Content { private final List mainContents = new ArrayList<>(); private Content side = null; private Content header = null; private Content footer = null; public BodyContents addMainContent(Content content) { mainContents.add(content); return this; } public BodyContents setSideContent(Content side) { this.side = Objects.requireNonNull(side); return this; } public BodyContents setHeader(Content header) { this.header = Objects.requireNonNull(header); return this; } public BodyContents setFooter(Content footer) { this.footer = footer; return this; } /** * {@inheritDoc} * * @implSpec This implementation always returns {@code false}. * * @return {@code false} */ @Override public boolean isEmpty() { return false; } @Override public boolean write(Writer out, String newline, boolean atNewline) throws IOException { return toContent().write(out, newline, atNewline); } /** * Returns the HTML for the contents of the BODY element. * * @return the HTML */ private Content toContent() { if (header == null) throw new NullPointerException(); return new ContentBuilder() .add(header) .add(HtmlTree.DIV(HtmlStyles.mainGrid) .add(side == null ? Text.EMPTY : side) .add(HtmlTree.MAIN() .add(mainContents) .add(footer == null ? Text.EMPTY : footer))); } }