Package com.google.common.net

Class HostSpecifier

  • @Beta
@GwtIncompatible
public final class HostSpecifier
extends Object
    A syntactically valid host specifier, suitable for use in a URI. This may be either a numeric IP address in IPv4 or IPv6 notation, or a domain name.

    Because this class is intended to represent host specifiers which can reasonably be used in a URI, the domain name case is further restricted to include only those domain names which end in a recognized public suffix; see InternetDomainName.isPublicSuffix() for details.

    Note that no network lookups are performed by any HostSpecifier methods. No attempt is made to verify that a provided specifier corresponds to a real or accessible host. Only syntactic and pattern-based checks are performed.

    If you know that a given string represents a numeric IP address, use InetAddresses to obtain and manipulate a InetAddress instance from it rather than using this class. Similarly, if you know that a given string represents a domain name, use InternetDomainName rather than this class.

    Since:
    5.0
    Author:
    Craig Berry

    • Method Detail

      • fromValid

        public static HostSpecifier fromValid​(String specifier)
        Returns a HostSpecifier built from the provided specifier, which is already known to be valid. If the specifier might be invalid, use from(String) instead.

        The specifier must be in one of these formats:

        • A domain name, like google.com
        • A IPv4 address string, like 127.0.0.1
        • An IPv6 address string with or without brackets, like [2001:db8::1] or 2001:db8::1
        Throws:
        IllegalArgumentException - if the specifier is not valid.

      • from

        public static HostSpecifier from​(String specifier)
                          throws ParseException
        Attempts to return a HostSpecifier for the given string, throwing an exception if parsing fails. Always use this method in preference to fromValid(String) for a specifier that is not already known to be valid.
        Throws:
        ParseException - if the specifier is not valid.

      • equals

        public boolean equals​(@CheckForNull
                      Object other)
        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:
        other - 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()
        Returns a string representation of the host specifier suitable for inclusion in a URI. If the host specifier is a domain name, the string will be normalized to all lower case. If the specifier was an IPv6 address without brackets, brackets are added so that the result will be usable in the host part of a URI.
        Overrides:
        toString in class Object
        Returns:
        a string representation of the object.