com.coyotegulch.jisp
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 KeyObject
s 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
Field Summary | |
---|---|
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.
|
Method Summary | |
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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 .
|
compareTo
when the invoking key is greater than the parameter key.
compareTo
when the invoking key has a different type from the parameter key.
compareTo
when the invoking key is less than the parameter key.
compareTo
when the invoking key equals the parameter key.
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.
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
String
representation of a KeyObject
.
Returns: The String
representation of a KeyObject
.