Design Patterns | Factory Method

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1. References
2. Example
   • The Product
   • The Concrete Product
   • The Factory
   • A simple class to test the Factory Method design pattern

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1. References
   • Definition: (source: http://en.wikipedia.org/wiki/Factory_method_pattern)
     
     Define an interface for creating an object, but let subclasses decide which class to instantiate.
     The Factory method lets a class defer instantiation it uses to subclasses.
2. Example
   • The Product:
     
     public interface Report { public String generate(final String data); }
     
   • The Concrete Product:
     
     public class ReportHtml implements Report { public String generate(final String csvData) { final StringBuilder htmlData = new StringBuilder(); if (csvData != null) { final String[] dataElements = csvData.split(","); for (final String dataElement : dataElements) { htmlData.append(String.format("<b>%s</b>", dataElement)); } } return htmlData.toString(); } }
     
   • The Factory:
     
     public class ReportFactory { public static Report getReport(final String type) { if ("html".equalsIgnoreCase(type)) { return new ReportHtml(); } return null; } }
     
   • A simple class to test the Factory Method design pattern:
     
     public class FactoryMethodPatternTest { public static void main(String[] args) { // create the report final Report report = ReportFactory.getReport("html"); // call methods final String htmlReport = report.generate("1,abc"); System.out.println(htmlReport); } }