Simple Syntax Highlighting

Have you ever wanted to embed syntax highlighted code in your app? In the above demo, I wanted to include the code that created the demo in order to help show how to “do-it-yourself”. Rather than switch from the demo to an IDE, I thought it was smoother and more focused to switch views within the actual application.

To get the syntax highlighted code, I used the open source jEdit Syntax Package. This package provides a JEditTextArea widget which handles all the details.

I like the componentized design of JEditTextArea – you can just drop the component right into your app, unlike trying to embed the NetBeans or Eclipse editor. You can tweak just about every aspect of the component, and you’ll probably need to because the default colors are a little wacky. I tweaked the text area in the app above like this:

        JEditTextArea textArea = new JEditTextArea();
        textArea.setTokenMarker(new JavaTokenMarker());
        textArea.setText(text);
        textArea.recalculateVisibleLines();
        textArea.setFirstLine(0);
        textArea.setElectricScroll(0);
        textArea.getPainter().setSelectionColor(
                UIManager.getColor("TextArea.selectionBackground"));

        SyntaxStyle[] styles = SyntaxUtilities.getDefaultSyntaxStyles();
        styles[Token.COMMENT1] = new SyntaxStyle(Color.GRAY,true,false);
        styles[Token.KEYWORD1] = new SyntaxStyle(new Color(0x000080),false,true);
        styles[Token.KEYWORD2] = new SyntaxStyle(new Color(0x000080),false,true);
        styles[Token.KEYWORD3] = new SyntaxStyle(new Color(0x000080),false,true);
        styles[Token.LITERAL1] = new SyntaxStyle(new Color(0x008000),false,true);
        styles[Token.LITERAL2] = new SyntaxStyle(new Color(0x000080),false,true);

        textArea.getPainter().setStyles(styles);

In the code above, I’ve set the text editor to render Java code, but there are a number of other languages available.

jEdit Syntax Package is a syntax highlighter – thats is, it doesn’t provide code completion, code folding or most of the other luxuries we’re used to. But when you need syntax highlighting, this package does the job.

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