Page 139 - DCAP408_WEB_PROGRAMMING

Unit 8: File I/O

The Basics Notes

Syntax Highlighting works like this: you give the text to the lexer, it goes through it and gives
it back to you piece by piece and tells you what color to make each piece.

Streams and Readers

The syntax lexers accept your document through Streams and Readers. Fortunately it is very
easy to turn just about anything into a Stream or a Reader. Java comes with many prebuilt
classes for this purpose. A FileReader or a StringReader could be used. The demo uses a custom
DocumentReader.

Tokens

The lexer returns Tokens. Tokens don’t tell you the actual color that the text should be, but they
do give you enough information to figure it out. The token contains such useful information as
the type of text, a description of the text, and the position of the text in the file.

Example: Basic Example
JavaLexer syntaxLexer = new JavaLexer(new StringReader(myDocumentText));
Token t;
while ((t = syntaxLexer.getNextToken()) != null){
// color the part of the document
// to which the token refers here.
}
The Demo uses a look-up hashtable to get the color of the text based on the description from the
token.
SimpleAttributeSet style;

style = new SimpleAttributeSet();
StyleConstants.setFontFamily(style, “Monospaced”);
StyleConstants.setFontSize(style, 12);
StyleConstants.setBackground(style, Color.white);
StyleConstants.setForeground(style, Color.black);
StyleConstants.setBold(style, false);
StyleConstants.setItalic(style, false);
styles.put(“body”, style);

style = new SimpleAttributeSet();
StyleConstants.setFontFamily(style, “Monospaced”);
StyleConstants.setFontSize(style, 12);
StyleConstants.setBackground(style, Color.white);
StyleConstants.setForeground(style, Color.blue);

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