Package com.coyotegulch.jisp

Class KeyObject

java.lang.Object
com.coyotegulch.jisp.KeyObject
All Implemented Interfaces:
Externalizable, Serializable
Direct Known Subclasses:
LongKey, StringKey
public abstract class KeyObject extends Object implements 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:

  • Field Summary

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

  • Constructor Summary

    Constructors
    Constructor
    Description
    KeyObject()
     

  • Method Summary

    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.
    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 Details

    • KEY_LESS

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

      See Also:

    • KEY_EQUAL

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

      See Also:

    • KEY_MORE

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

      See Also:

    • 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:

  • Constructor Details

    • KeyObject

      public KeyObject()

  • Method Details

    • 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:

    • toString

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

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