Package com.helger.commons.hierarchy.visit

Interface IHierarchyVisitorCallback<DATATYPE>

  • Type Parameters:
    DATATYPE - The type of object to be iterated.
    All Superinterfaces:
    ICallback
    All Known Implementing Classes:
    DefaultHierarchyVisitorCallback
    public interface IHierarchyVisitorCallback<DATATYPE>
extends ICallback
    Base interface with callbacks for visiting a hierarchy.
    Author:
    Philip Helger

    • Method Detail

      • begin

        default void begin()
        Called before the tree walking starts.

      • getLevel

        @Nonnegative
int getLevel()
        Returns:
        The level of the current node within the hierarchy. Always ≥ 0. The root item has level 0.

      • onLevelDown

        default void onLevelDown()
        Called before the tree walker descends into the next tree level. After this call getLevel() should return a value increased by 1.

      • onLevelUp

        default void onLevelUp()
        Called after the tree walker ascends into the previous tree level. After this call getLevel() should return a value decreased by 1.

      • onItemBeforeChildren

        @Nonnull
EHierarchyVisitorReturn onItemBeforeChildren​(DATATYPE aItem)
        Called before children of the current item are visited. This method is also to be called if no children are present at all.
        Parameters:
        aItem - The current item. May be null.
        Returns:
        A non-null status code that determines how to continue iteration.

      • onItemAfterChildren

        @Nonnull
EHierarchyVisitorReturn onItemAfterChildren​(DATATYPE aItem)
        Called after eventual children of the current item were visited. This method is also to be called if no children are present at all. This method has always to be called if onItemBeforeChildren(Object) was called.
        Parameters:
        aItem - The current item. May be null.
        Returns:
        A non-null status code that determines how to continue iteration.

      • end

        default void end()
        Called after the tree walking ended.