Package com.coyotegulch.jisp

Class KeyObject

  • All Implemented Interfaces:
    java.io.Externalizable, java.io.Serializable
    Direct Known Subclasses:
    LongKey, StringKey
    public abstract class KeyObject
extends java.lang.Object
implements java.io.Externalizable
    KeyObject defines an characteristics of an object to be used as a key * in an ObjectIndex. Since Java lacks true generic types, it is up to * the programmer to ensure that all KeyObjects have the same concrete type * for a given ObjectIndex. Each ObjectIndex supports a single * concrete KeyObject type. *

    * Concrete KeyObject classes must always produce a

    See Also:
    ObjectIndex, Serialized Form

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int KEY_EQUAL
      Returned by compareTo when the invoking key is greater than the parameter key.
      static int KEY_ERROR
      Returned by compareTo when the invoking key has a different type from the parameter key.
      static int KEY_LESS
      Returned by compareTo when the invoking key is less than the parameter key.
      static int KEY_MORE
      Returned by compareTo when the invoking key equals the parameter key.

    • Constructor Summary

      Constructors 
      Constructor Description
      KeyObject()  

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      abstract int compareTo​(KeyObject key)
      Compares the invoking object to key, returning one of the KEY_* constants based on the relationship of the two keys.
      abstract KeyObject makeNullKey()
      Returns a "null" (i.e., blank) key, to be used as a space-holder in certain kinds of ObjectIndexes.
      java.lang.String toString()
      Returns the String representation of a KeyObject.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

      • Methods inherited from interface java.io.Externalizable

        readExternal, writeExternal

    • Field Detail

      • KEY_LESS

        public static final int KEY_LESS
        Returned by compareTo when the invoking key is less than the parameter key.

        See Also:
        Constant Field Values

      • KEY_EQUAL

        public static final int KEY_EQUAL
        Returned by compareTo when the invoking key is greater than the parameter key.

        See Also:
        Constant Field Values

      • KEY_MORE

        public static final int KEY_MORE
        Returned by compareTo when the invoking key equals the parameter key.

        See Also:
        Constant Field Values

      • KEY_ERROR

        public static final int KEY_ERROR
        Returned by compareTo when the invoking key has a different type from the parameter key.

        See Also:
        Constant Field Values

    • Constructor Detail

      • KeyObject

        public KeyObject()

    • Method Detail

      • compareTo

        public abstract int compareTo​(KeyObject key)
        Compares the invoking object to key, returning one of the KEY_* constants based on the relationship of the two keys.

        Parameters:
        key - The key value to be compared against the invoking key. * @return One of the KEY_* constants based on the relationship of the two keys.

      • makeNullKey

        public abstract KeyObject makeNullKey()
        Returns a "null" (i.e., blank) key, to be used as a space-holder in certain kinds of ObjectIndexes.

        For example, a BTreeIndex maintains a set of index pages that must contain a set number of fixed-length keys. When creating a BTreeIndex, you must provide a "null" key, using the makeNullKey method.

        Returns:
        A "null" (i.e., blank) key constant.
        See Also:
        BTreeIndex

      • toString

        public java.lang.String toString()
        Returns the String representation of a KeyObject.

        Overrides:
        toString in class java.lang.Object
        Returns:
        The String representation of a KeyObject.