Package com.coyotegulch.jisp
Class KeyObject
- java.lang.Object
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- com.coyotegulch.jisp.KeyObject
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- All Implemented Interfaces:
java.io.Externalizable
,java.io.Serializable
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 anObjectIndex
. Since Java lacks true generic types, it is up to * the programmer to ensure that allKeyObject
s have the same concrete type * for a givenObjectIndex
. EachObjectIndex
supports a single * concreteKeyObject
type. ** Concrete
KeyObject
classes must always produce a- See Also:
ObjectIndex
, Serialized Form
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Field Summary
Fields Modifier and Type Field Description static int
KEY_EQUAL
Returned bycompareTo
when the invoking key is greater than the parameter key.static int
KEY_ERROR
Returned bycompareTo
when the invoking key has a different type from the parameter key.static int
KEY_LESS
Returned bycompareTo
when the invoking key is less than the parameter key.static int
KEY_MORE
Returned bycompareTo
when the invoking key equals the parameter key.
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Constructor Summary
Constructors Constructor Description KeyObject()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description abstract int
compareTo(KeyObject key)
Compares the invoking object tokey
, returning one of theKEY_*
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 ofObjectIndexes
.java.lang.String
toString()
Returns theString
representation of aKeyObject
.
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Field Detail
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KEY_LESS
public static final int KEY_LESS
Returned bycompareTo
when the invoking key is less than the parameter key.- See Also:
- Constant Field Values
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KEY_EQUAL
public static final int KEY_EQUAL
Returned bycompareTo
when the invoking key is greater than the parameter key.- See Also:
- Constant Field Values
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KEY_MORE
public static final int KEY_MORE
Returned bycompareTo
when the invoking key equals the parameter key.- See Also:
- Constant Field Values
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KEY_ERROR
public static final int KEY_ERROR
Returned bycompareTo
when the invoking key has a different type from the parameter key.- See Also:
- Constant Field Values
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Method Detail
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compareTo
public abstract int compareTo(KeyObject key)
Compares the invoking object tokey
, returning one of theKEY_*
constants based on the relationship of the two keys.- Parameters:
key
- The key value to be compared against the invoking key. * @return One of theKEY_*
constants based on the relationship of the two keys.
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makeNullKey
public abstract KeyObject makeNullKey()
Returns a "null" (i.e., blank) key, to be used as a space-holder in certain kinds ofObjectIndexes
.For example, a
BTreeIndex
maintains a set of index pages that must contain a set number of fixed-length keys. When creating aBTreeIndex
, you must provide a "null" key, using themakeNullKey
method.- Returns:
- A "null" (i.e., blank) key constant.
- See Also:
BTreeIndex
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toString
public java.lang.String toString()
Returns theString
representation of aKeyObject
.- Overrides:
toString
in classjava.lang.Object
- Returns:
- The
String
representation of aKeyObject
.
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