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==Sample Code==
[[Image:beveragedecorator.png|300 px|thumb|Beverage Decorator UML diagram]]
Beverage is the abstract component class
public abstract class Beverage {
//static abstract double size();
}
[[Image:wrappingdecorator2.png|300 px|thumb|Figure 1 wrapping Decorator classes]]
Leaf classes that inherit from Beverage class
}
}
[[Image:beverageDecoratorWholePic.png|300 px|thumb|The Big Picture]]
Condiment Decorator class
}
}
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==Example==
[[Image:javaIOdecorator2.png|500 px|thumb|Java I/O classes]] Java I/O [http://java.sun.com/javase/6/docs/api/java/io/package-frame.html API] JDK 6u1 [http://www.java.net/download/jdk6/6u1/promoted/b03/jdk-6u1-ea-src-b03-jrl-19_jan_2007.jar Source] under the [http://www.java.net/jrl.csp JRL license] extract: java -jar jdk-6u1-ea-src-b03-jrl-19_jan_2007.jar java.io location: j2se/src/share/classes/java/io/ ----Abstract Component class: public abstract class InputStream { abstract int read(); }Concrete Component class: class FileInputStream extends InputStream { public int read(); }Decorator class: public class FilterInputStream extends InputStream { { //<span style="color:red">Local variable for storing the reference of the concrete component class</span> protected volatile InputStream in; protected FilterInputStream(InputStream in) { this.in = in; } public int read() { return in.read(); } }Concrete Decorator class: public class PushbackInputStream extends FilterInputStream { public PushbackInputStream(InputStream in, int size) { super(in); //<span style="color:red">Calls the FilterInputStream class and stores the reference of InputStream</span> if (size <= 0) { throw new IllegalArgumentException("size <= 0"); } this.buf = new byte[size]; this.pos = size; } public int read(){ ensureOpen(); if (pos < buf.length) { return buf[pos++] & 0xff; } return super.read(); } } ---- [[Image:mpclDecorator.png|400 px|thumb|MPCL]] Multi purpose class library (MPCL) [http://www.google.com/codesearch?hl=en&q=show:QUdC7Hs10WU:9dcfaUrTzRs:gcPYjQUkI_I&sa=N&ct=rd&cs_p=http://www.uesqlc.org/download/mpcl/mpcl-11.0.2.zip&cs_f=mpcl-11.0.2/src/java/lib/org/mpcl/nui/table/TDecoratorTableCellRenderer.java Source Code] GPL license ---- Concrete Components <br>TDecoratorTableCellRenderer: /**Decorating our Beverages *Java I Table cell renderer that decorates a delegate cell renderer. It implements * the Decorator design pattern. */ public class TDecoratorTableCellRenderer implements TableCellRenderer { /// Delegate table cell renderer. private TableCellRenderer tDelegateTableCellRenderer; /// Table cell decorator. private ITableCellDecorator tTableCellDecorator; // // C O N S T R U C T O R S // /** * Builds a new instance. * @param tDELEGATE_TABLE_CELL_RENDERER The delegate table cell renderer. * @param tTABLE_CELL_DECORATOR Table cell decorator. */ public TDecoratorTableCellRenderer ( TableCellRenderer tDELEGATE_TABLE_CELL_RENDERER , ITableCellDecorator tTABLE_CELL_DECORATOR ) { tDelegateTableCellRenderer = tDELEGATE_TABLE_CELL_RENDERER; tTableCellDecorator = tTABLE_CELL_DECORATOR; } DefaultTableCellRenderer: public class DefaultTableCellRenderer extends JLabel implements TableCellRenderer, Serializable { /** * Creates a default table cell renderer. */ public DefaultTableCellRenderer() { super(); setOpaque(true); setBorder(getNoFocusBorder()); } } TDateTableCellRenderer: public class TDateTableCellRenderer extends DefaultTableCellRenderer { /// Date format. private DateFormat tDateFormat; // // C O N S T R U C T O R S // /** * Sets the String object for the cell being rendered to value. * @param tVALUE The value for this cell; if \a tVALUE is \a null it sets the * the text value to an empty string. * @see javax.swing.table.DefaultTableCellRenderer#setValue() */ protected void setValue (Object tVALUE) { setText (( tVALUE == null ) ? "" : tDateFormat.format ((Date) tVALUE)); } TPopulationTableCellRenderer: /// Table cell renderer for \a TPopulation objects. public class TPopulationTableCellRenderer extends DefaultTableCellRenderer { /// Number format. public NumberFormat tNumberFormat; // // C O N S T R U C T O R S // /** * Sets the String object for the cell being rendered to value. * @param tVALUE The value for this cell; if \a tVALUE is \a null it sets the * the text value to an empty string. * @see javax.swing.table.DefaultTableCellRenderer#setValue() */ protected void setValue (Object tVALUE) { if ( tNumberFormat == null) { tNumberFormat = TDecimalFormat._getPopulationInstance(); } setText (( tVALUE == null ) ? "" : tNumberFormat.format (((TPopulation) tVALUE).intValue())); } // // C O N S T R U C T OR S // /// Builds a new instance. public TPopulationTableCellRenderer() { super(); setHorizontalAlignment (DefaultTableCellRenderer.RIGHT); } } // class TPopulationTableCellRenderer ==Contributions==[http://zenit.senecac.on.ca/wiki/index.php/Talk:Adapter Adapter pattern] in Eclipse
==References==
Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1994). Design Patterns: Elements of Reusable Object-Oriented Software. Addison-Wesley. ISBN 0-201-63361-2.
Freeman, Eric; Freeman, Elisabeth; Sierra, Kathy; Bates, Bert (2004). Head First Design Patterns. O`Reilly. ISBN 0-596-00712-4.
http://www.dofactory.com/Patterns/PatternDecorator.aspx
