在Java中，可以使用JavaFX的SyntaxHighlighter类来实现代码高亮显示。以下是一个简单的例子，演示如何使用JavaFX来设置代码高亮显示方案：

import javafx.scene.control.TextArea;
import javafx.scene.layout.StackPane;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.scene.text.TextFlow;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.ScrollPane;
import org.fxmisc.richtext.CodeArea;
import org.fxmisc.richtext.LineNumberFactory;
import org.fxmisc.richtext.model.StyleSpans;
import org.fxmisc.richtext.model.StyleSpansBuilder;
import org.reactfx.Subscription;

import java.time.Duration;
import java.util.Collection;
import java.util.Collections;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class SyntaxHighlighting extends Application {

    private static final String[] KEYWORDS = new String[]{
            "abstract", "assert", "boolean", "break", "byte",
            "case", "catch", "char", "class", "const",
            "continue", "default", "do", "double", "else",
            "enum", "extends", "final", "finally", "float",
            "for", "goto", "if", "implements", "import",
            "instanceof", "int", "interface", "long", "native",
            "new", "package", "private", "protected", "public",
            "return", "short", "static", "strictfp", "super",
            "switch", "synchronized", "this", "throw", "throws",
            "transient", "try", "void", "volatile", "while"
    };

    private static final String KEYWORD_PATTERN = "\\b(" + String.join("|", KEYWORDS) + ")\\b";
    private static final String PAREN_PATTERN = "\\(|\\)";
    private static final String BRACE_PATTERN = "\\{|\\}";
    private static final String BRACKET_PATTERN = "\\[|\\]";
    private static final String SEMICOLON_PATTERN = "\\;";
    private static final String STRING_PATTERN = "\"([^\"\\\\]|\\\\.)*\"";
    private static final String COMMENT_PATTERN = "//[^\n]*" + "|" + "/\\*(.|\\R)*?\\*/";

    private static final Pattern PATTERN = Pattern.compile(
            "(?<KEYWORD>" + KEYWORD_PATTERN + ")"
            + "|(?<PAREN>" + PAREN_PATTERN + ")"
            + "|(?<BRACE>" + BRACE_PATTERN + ")"
            + "|(?<BRACKET>" + BRACKET_PATTERN + ")"
            + "|(?<SEMICOLON>" + SEMICOLON_PATTERN + ")"
            + "|(?<STRING>" + STRING_PATTERN + ")"
            + "|(?<COMMENT>" + COMMENT_PATTERN + ")"
    );

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) {

        // Create a JavaFX TextArea
        TextArea textArea = new TextArea();
        textArea.setWrapText(true);
        textArea.setFont(Font.font("Courier New", 14));

        // Set up syntax highlighting
        Subscription cleanupWhenNoLongerNeedIt = setupSyntaxHighlighting(textArea);

        // Add the TextArea to a ScrollPane
        ScrollPane scrollPane = new ScrollPane(textArea);
        scrollPane.setFitToHeight(true);
        scrollPane.setFitToWidth(true);

        // Create a JavaFX StackPane to hold the ScrollPane
        StackPane stackPane = new StackPane(scrollPane);

        // Create a JavaFX Scene with the StackPane as the root node
        Scene scene = new Scene(stackPane, 800, 600);

        // Set the Scene to the Stage
        stage.setScene(scene);

        // Show the Stage
        stage.show();

        // Clean up the syntax highlighting when the Stage is closed
        stage.setOnCloseRequest(event -> cleanupWhenNoLongerNeedIt.unsubscribe());
    }

    private static Subscription setupSyntaxHighlighting(TextArea textArea) {
        CodeArea codeArea = new CodeArea();
        codeArea.textProperty().bindBidirectional(textArea.textProperty());

        codeArea.setParagraphGraphicFactory(LineNumberFactory.get(codeArea));
        codeArea.setStyleSpansFactory(this::computeHighlighting);

        Subscription cleanupWhenNoLongerNeedIt = codeArea
                .multiPlainChanges()
                .successionEnds(Duration.ofMillis(500))
                .subscribe(ignore -> codeArea.setStyleSpans(0, computeHighlighting(codeArea.getText())));

        return cleanupWhenNoLongerNeedIt;
    }

    private static StyleSpans<Collection<String>> computeHighlighting(String text) {
        Matcher matcher = PATTERN.matcher(text);
        int lastKwEnd = 0;
        StyleSpansBuilder<Collection<String>> spansBuilder = new StyleSpansBuilder<>();
        while (matcher.find()) {
            String styleClass =
                    matcher.group("KEYWORD") != null ? "keyword" :
                    matcher.group("PAREN") != null ? "paren" :
                    matcher.group("BRACE") != null ? "brace" :
                    matcher.group("BRACKET") != null ? "bracket" :
                    matcher.group("SEMICOLON") != null ? "semicolon" :
                    matcher.group("STRING") != null ? "string" :
                    matcher.group("COMMENT") != null ? "comment" :
                    null;
            assert styleClass != null;
            spansBuilder.add(Collections.emptyList(), matcher.start() - lastKwEnd);
            spansBuilder.add(Collections.singleton(styleClass), matcher.end() - matcher.start());
            lastKwEnd = matcher.end();
        }
        spansBuilder.add(Collections.emptyList(), text.length() - lastKwEnd);
        return spansBuilder.create();
    }
}

在上述代码中，我们使用了JavaFX提供的CodeArea组件作为代码编辑器，并使用StyleSpans类来设置代码高亮的样式。

在computeHighlighting方法中，我们使用正则表达式来匹配Java代码中的不同部分（关键字、括号、字符串、注释等），并给它们应用不同的样式。

为了使代码高亮显示生效，我们需要将TextArea组件绑定到CodeArea组件，并在CodeArea的multiPlainChanges方法中设置样式。

最后，将TextArea组件放入一个ScrollPane中，并将ScrollPane放入一个StackPane中，最后将StackPane作为根节点创建JavaFX场景。