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
    Returned by compareTo when the invoking key is greater than the parameter key.
    static final int
    Returned by compareTo when the invoking key has a different type from the parameter key.
    static final int
    Returned by compareTo when the invoking key is less than the parameter key.
    static final int
    Returned by compareTo when the invoking key equals the parameter key.
  • Constructor Summary

    Constructors
    Constructor
    Description
     
  • Method Summary

    Modifier and Type
    Method
    Description
    abstract int
    Compares the invoking object to key, returning one of the KEY_* constants based on the relationship of the two keys.
    abstract KeyObject
    Returns a "null" (i.e., blank) key, to be used as a space-holder in certain kinds of ObjectIndexes.
    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.