Module is.codion.swing.common.model.tools
Package is.codion.swing.common.model.tools.randomizer

Interface ItemRandomizer<T>

Type Parameters:
T - the type of item this random item model returns
public interface ItemRandomizer<T>
ItemRandomizer provides a way to randomly choose an item based on a weight value. 
 Object one = new Object();
 Object two = new Object();
 Object three = new Object();

 ItemRandomizer model = ItemRandomizer.itemRandomizer(Arrays.asList(one, two, three));

 model.setWeight(one, 10);
 model.setWeight(two, 60);
 model.setWeight(three, 30);

 //10% chance of getting 'one', 60% chance of getting 'two' and 30% chance of getting 'three'.
 Object random = model.randomItem();
For instances use the following factory functions: itemRandomizer(Collection), boundedItemRandomizer(Collection), boundedItemRandomizer(Collection, int)

  • Method Details

    • itemCount

      int itemCount()
      Returns:
      the number of items in this model.

    • items

      Collection<ItemRandomizer.RandomItem<T>> items()
      Returns:
      the items in this model.

    • weight

      int weight(T item)
      Returns the weight of the given item.
      Parameters:
      item - the item
      Returns:
      the item weight

    • setWeight

      void setWeight(T item, int weight)
      Sets the weight of the given item
      Parameters:
      item - the item
      weight - the value

    • randomItem

      T randomItem()
      Fetches a random item from this model based on the item weights.
      Returns:
      a randomly chosen item.

    • weightRatio

      double weightRatio(T item)
      Returns this items share in the total weights as a floating point number between 0 and 1
      Parameters:
      item - the item
      Returns:
      the ratio of the total weights held by the given item

    • incrementWeight

      void incrementWeight(T item)
      Increments the weight of the given item by one
      Parameters:
      item - the item

    • decrementWeight

      void decrementWeight(T item)
      Decrements the weight of the given item by one
      Parameters:
      item - the item
      Throws:
      IllegalStateException - in case the weight is 0

    • isItemEnabled

      boolean isItemEnabled(T item)
      Parameters:
      item - the item
      Returns:
      true if the item is enabled

    • setItemEnabled

      void setItemEnabled(T item, boolean enabled)
      Parameters:
      item - the item
      enabled - true if the item should be enabled

    • itemRandomizer

      static <T> ItemRandomizer<T> itemRandomizer(Collection<ItemRandomizer.RandomItem<T>> items)
      Instantiates a new ItemRandomizer.
      Type Parameters:
      T - the item type
      Parameters:
      items - the items to randomize
      Returns:
      a new ItemRandomizer

    • boundedItemRandomizer

      static <T> ItemRandomizer<T> boundedItemRandomizer(Collection<T> items)
      Instantiates a new ItemRandomizer with the added constraint that the total item weights can not exceed a defined maximum. When the weight of one item is incremented the weight of another is decremented in a round-robin kind of fashion and when an item weight is decremented the weight of another is incremented.
      Instantiates a new ItemRandomizer with the maximum total weights as 100.
      Type Parameters:
      T - the item type
      Parameters:
      items - the items
      Returns:
      a new ItemRandomizer

    • boundedItemRandomizer

      static <T> ItemRandomizer<T> boundedItemRandomizer(Collection<T> items, int maximumTotalWeights)
      Instantiates a new ItemRandomizer with the added constraint that the total item weights can not exceed a defined maximum. When the weight of one item is incremented the weight of another is decremented in a round-robin kind of fashion and when an item weight is decremented the weight of another is incremented.
      Type Parameters:
      T - the item type
      Parameters:
      items - the items
      maximumTotalWeights - the maximum total weights
      Returns:
      a new ItemRandomizer