Android Design Patterns and Best Practice

The criteria pattern

The criteria design pattern provides a clear and concise technique for filtering objects according to set criteria. It can be a very powerful tool as this next exercise will demonstrate.

In this example, we will apply a filter pattern to sort through a list of ingredients and filter them according to whether they are vegetarian and where they are produced:

1. Begin by creating the filter interface, like so:

   public interface Filter { 
    
       List<Ingredient> meetCriteria(List<Ingredient> ingredients); 
   } 
   

2. Next add the ingredient class, like this:

   public class Ingredient { String name; String local; boolean vegetarian; public Ingredient(String name, String local, boolean vegetarian){ this.name = name; this.local = local; this.vegetarian = vegetarian; ...