Package com.google.common.graph

Class ElementOrder<T>

  • @Beta
@Immutable
public final class ElementOrder<T>
extends Object
    Used to represent the order of elements in a data structure that supports different options for iteration order guarantees.

    Example usage: 

    
 MutableGraph<Integer> graph =
     GraphBuilder.directed().nodeOrder(ElementOrder.<Integer>natural()).build();
    Since:
    20.0
    Author:
    Joshua O'Madadhain

    • Method Detail

      • unordered

        public static <S> ElementOrder<S> unordered()
        Returns an instance which specifies that no ordering is guaranteed.

      • stable

        public static <S> ElementOrder<S> stable()
        Returns an instance which specifies that ordering is guaranteed to be always be the same across iterations, and across releases. Some methods may have stronger guarantees.

        This instance is only useful in combination with incidentEdgeOrder, e.g. graphBuilder.incidentEdgeOrder(ElementOrder.stable()).

        In combination with incidentEdgeOrder

        incidentEdgeOrder(ElementOrder.stable()) guarantees the ordering of the returned collections of the following methods:

        • For Graph and ValueGraph:
          • edges(): Stable order
          • adjacentNodes(node): Connecting edge insertion order
          • predecessors(node): Connecting edge insertion order
          • successors(node): Connecting edge insertion order
          • incidentEdges(node): Edge insertion order
        • For Network:
          • adjacentNodes(node): Stable order
          • predecessors(node): Connecting edge insertion order
          • successors(node): Connecting edge insertion order
          • incidentEdges(node): Stable order
          • inEdges(node): Edge insertion order
          • outEdges(node): Edge insertion order
          • adjacentEdges(edge): Stable order
          • edgesConnecting(nodeU, nodeV): Edge insertion order
        Since:
        29.0

      • insertion

        public static <S> ElementOrder<S> insertion()
        Returns an instance which specifies that insertion ordering is guaranteed.

      • natural

        public static <S extends Comparable<? super S>> ElementOrder<S> natural()
        Returns an instance which specifies that the natural ordering of the elements is guaranteed.

      • sorted

        public static <S> ElementOrder<S> sorted​(Comparator<S> comparator)
        Returns an instance which specifies that the ordering of the elements is guaranteed to be determined by comparator.

      • equals

        public boolean equals​(@Nullable Object obj)
        Description copied from class: java.lang.Object
        Indicates whether some other object is "equal to" this one.

        The equals method implements an equivalence relation on non-null object references:

        • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
        • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
        • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
        • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
        • For any non-null reference value x, x.equals(null) should return false.

        The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

        Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

        Overrides:
        equals in class Object
        Parameters:
        obj - the reference object with which to compare.
        Returns:
        true if this object is the same as the obj argument; false otherwise.
        See Also:
        Object.hashCode(), HashMap

      • hashCode

        public int hashCode()
        Description copied from class: java.lang.Object
        Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

        The general contract of hashCode is:

        • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
        • If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
        • It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

        As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (The hashCode may or may not be implemented as some function of an object's memory address at some point in time.)

        Overrides:
        hashCode in class Object
        Returns:
        a hash code value for this object.
        See Also:
        Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

      • toString

        public String toString()
        Description copied from class: java.lang.Object
        Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

        The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of: 

         getClass().getName() + '@' + Integer.toHexString(hashCode())
        Overrides:
        toString in class Object
        Returns:
        a string representation of the object.