Top Description Fields Constructors Methods
org.hsqldb.types

public Class JavaObjectData

extends Object
Class Inheritance
Known Direct Subclasses
org.hsqldb.types.JavaObjectDataInternal
Imports
java.io.Serializable, org.hsqldb.error.Error, .ErrorCode, org.hsqldb.lib.InOutUtil
Represents of an instance of an OTHER field value.

Prior to 1.7.0 there were problems storing Objects of normal column types in columns of the type OTHER. In 1.7.0 changes were made to allow this, but as all the conversion took place inside the engine, it introduced a requirement for all classes for objects stored in OTHER columns to be available on the runtime class path of the engine.

In 1.7.2, the introduction of real prepared statement support allows us revert to the pre 1.7.0 behaviour without the artificial limitations.

The classes for stored objects need not be available to open and operate the database in general. The classes need to be available only if a conversion from one of these objects to another type is performed inside the engine while operating the database. The current limitation is that in SQL statements, values of type String (CHARACTER and related SQL types) cannot be stored in columns of type OTHER. This limitation does not exist for String values assigned to PreparedStatement variables.

Author
Fred Toussi (fredt@users dot sourceforge.net)
Since
1.7.2
Version
2.3.4

Field Summary

Modifier and TypeField and Description
private byte[]
data

Constructor Summary

AccessConstructor and Description
pack-priv
JavaObjectData()

public
JavaObjectData(byte[] data)

Constructor used inside the engine when an already serialized Object is read from a file (.log, .script, .data or text table source).

public
JavaObjectData(Serializable o)

Constructor used inside the engine to convert an Object into an object of type OTHER.

Method Summary

Modifier and TypeMethod and Description
public boolean
equals(Object other)

Overrides java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

public byte[]
getBytes()

public int
getBytesLength()

public Object
getObject()

This method is called from classes implementing the JDBC interfaces.

public int
hashCode()

Overrides java.lang.Object.hashCode.

Returns a hash code value for this object.

public String

Returns:

a String representation of this object.
toString()

Overrides java.lang.Object.toString.

Returns String representation of this object.

Inherited from java.lang.Object:
clonefinalizegetClassnotifynotifyAllwaitwaitwait

Field Detail

databack to summary
private byte[] data

Constructor Detail

JavaObjectDataback to summary
pack-priv JavaObjectData()
JavaObjectDataback to summary
public JavaObjectData(byte[] data)

Constructor used inside the engine when an already serialized Object is read from a file (.log, .script, .data or text table source).

JavaObjectDataback to summary
public JavaObjectData(Serializable o)

Constructor used inside the engine to convert an Object into an object of type OTHER. Used also with JDBC setParameter(). If parameter serialize is true, the Object is serialized for storage.

Method Detail

equalsback to summary
public boolean equals(Object other)

Overrides java.lang.Object.equals.

Doc from java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

  • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
  • For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

getBytesback to summary
public byte[] getBytes()
getBytesLengthback to summary
public int getBytesLength()
getObjectback to summary
public Object getObject()

This method is called from classes implementing the JDBC interfaces. Inside the engine it is used for conversion from a value of type OTHER to another type. It will throw if the OTHER is an instance of a class that is not available.

hashCodeback to summary
public int hashCode()

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
  • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
toStringback to summary
public String toString()

Overrides java.lang.Object.toString.

Returns String representation of this object.

Returns:String

a String representation of this object.