com.coyotegulch.jisp

Class KeyObject

java.lang.Object

com.coyotegulch.jisp.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 and 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 and Description
KeyObject()

Method Summary

Modifier and Type	Method and 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.