Question

Please see the code below . Here based on the String constants , I am instantiating different types of component classes . Now there are atleast 15 different types of String constants . So if I follow this pattern there will be 15 different cases and those many if -else blocks . Is there a better way of doing this ? I want to have the flexibility of being able to add and delete cases by doing the minimum possible code change.

public UIComponent initCellEditor(String editorType) {
        UIComponent editControl = null;
        if ("TbComboBoxCellType".equals(editorType)) {
          editControl = new WebListEntryField();
          editControl.setId("ComboBox");
        } else if ("TbStringCellType".equals(editorType)) {
          editControl = new WebInputEntryField();
          editControl.setId("String");
        } else if ("TbDateCellType".equals(editorType)) {
          editControl = new WebDateEntryField();
          editControl.setId("Date");
        } else if ("TbDateTimeCellType".equals(editorType)) {
          editControl = new WebDateTimeEntryField();
          editControl.setId("DateTime");
        } else {
          //default editor is allways a text input
          editControl = new WebInputEntryField();
          editControl.setId("Input");
        }
        return editControl;
      }

P.S: We are using JDK 6 . So can’t use switch on String feature.

Answer 1

you could transform those string constants to Enums, and add a builder method on the enum, for example

public enum CellType {
      TbComboBox {
         @Override
         public UIComponent newComponent() {
            return new xxx();
         }
      },
      TbDate {
         @Override
         public UIComponent newComponent() {
            return new xxx();
         }
      }

      public abstract UIComponent newComponent();
}

The beauty of this approach is that it replaces IFs with polymorphism (which in my opnion is very OO).

---

Sorry, I just realised that you have a default type (the last else in your code), so you might need to add an if somewhere :(.