org.apache.derby.catalog.types
Class TypeDescriptorImpl

java.lang.Object
  org.apache.derby.catalog.types.TypeDescriptorImpl

All Implemented Interfaces:

java.io.Externalizable, Formatable, java.io.Serializable, TypeDescriptor, TypedFormat

public class TypeDescriptorImpl

extends java.lang.Object

implements TypeDescriptor, Formatable

See Also:

Serialized Form

Field Summary

private boolean	isNullable
private int	maximumWidth
private int	precision
private int	scale
private BaseTypeIdImpl	typeId This class implements Formatable.

Fields inherited from interface org.apache.derby.catalog.TypeDescriptor

MAXIMUM_WIDTH_UNKNOWN

Constructor Summary

TypeDescriptorImpl()
Public niladic constructor.

TypeDescriptorImpl(BaseTypeIdImpl typeId, boolean isNullable, int maximumWidth)
Constructor for use with non-numeric types

TypeDescriptorImpl(BaseTypeIdImpl typeId, int precision, int scale, boolean isNullable, int maximumWidth)
Constructor for use with numeric types

TypeDescriptorImpl(TypeDescriptorImpl source, boolean isNullable, int maximumWidth)
Constructor for internal uses only

TypeDescriptorImpl(TypeDescriptorImpl source, int precision, int scale, boolean isNullable, int maximumWidth)
Constructor for internal uses only.

Method Summary

boolean	equals(java.lang.Object object) Compare if two TypeDescriptors are exactly the same
int	getJDBCTypeId() Get the jdbc type id for this type.
int	getMaximumWidth() Returns the maximum width of the type.
int	getMaximumWidthInBytes() Return the length of this type in bytes.
int	getPrecision() Returns the number of decimal digits for the datatype, if applicable.
int	getScale() Returns the number of digits to the right of the decimal for the datatype, if applicable.
java.lang.String	getSQLstring() Converts this data type descriptor (including length/precision) to a string.
int	getTypeFormatId() Get the formatID which corresponds to this class.
BaseTypeIdImpl	getTypeId() Get the type Id stored within this type descriptor.
java.lang.String	getTypeName() Gets the name of this datatype.
boolean	isNullable() Returns TRUE if the datatype can contain NULL, FALSE if not.
void	readExternal(java.io.ObjectInput in) Read this object from a stream of stored objects.
void	setNullability(boolean nullable) Set the nullability of the datatype described by this descriptor
java.lang.String	toString()
void	writeExternal(java.io.ObjectOutput out) Write this object to a stream of stored objects.

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

typeId

private BaseTypeIdImpl typeId

This class implements Formatable. That means that it can write itself to and from a formatted stream. If you add more fields to this class, make sure that you also write/read them with the writeExternal()/readExternal() methods. If, inbetween releases, you add more fields to this class, then you should bump the version number emitted by the getTypeFormatId() method.

precision

private int precision

scale

private int scale

isNullable

private boolean isNullable

maximumWidth

private int maximumWidth

Constructor Detail

TypeDescriptorImpl

public TypeDescriptorImpl()

Public niladic constructor. Needed for Formatable interface to work.

TypeDescriptorImpl

public TypeDescriptorImpl(BaseTypeIdImpl typeId,
                          int precision,
                          int scale,
                          boolean isNullable,
                          int maximumWidth)

Constructor for use with numeric types

Parameters:

typeId - The typeId of the type being described

precision - The number of decimal digits.

scale - The number of digits after the decimal point.

isNullable - TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth - The maximum number of bytes for this datatype

TypeDescriptorImpl

public TypeDescriptorImpl(BaseTypeIdImpl typeId,
                          boolean isNullable,
                          int maximumWidth)

Constructor for use with non-numeric types

Parameters:

typeId - The typeId of the type being described

isNullable - TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth - The maximum number of bytes for this datatype

TypeDescriptorImpl

public TypeDescriptorImpl(TypeDescriptorImpl source,
                          int precision,
                          int scale,
                          boolean isNullable,
                          int maximumWidth)

Constructor for internal uses only. (This is useful when the precision and scale are potentially wider than those in the source, like when determining the dominant data type.)

Parameters:

source - The DTSI to copy

precision - The number of decimal digits.

scale - The number of digits after the decimal point.

isNullable - TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth - The maximum number of bytes for this datatype

TypeDescriptorImpl

public TypeDescriptorImpl(TypeDescriptorImpl source,
                          boolean isNullable,
                          int maximumWidth)

Constructor for internal uses only

Parameters:

source - The DTSI to copy

isNullable - TRUE means it could contain NULL, FALSE means it definitely cannot contain NULL.

maximumWidth - The maximum number of bytes for this datatype

Method Detail

getMaximumWidth

public int getMaximumWidth()

Description copied from interface: TypeDescriptor

Returns the maximum width of the type. This may have different meanings for different types. For example, with char, it means the maximum number of characters, while with int, it is the number of bytes (i.e. 4).

Specified by:

getMaximumWidth in interface TypeDescriptor

Returns:

the maximum length of this Type; -1 means "unknown/no max length"

See Also:

TypeDescriptor.getMaximumWidth()

getMaximumWidthInBytes

public int getMaximumWidthInBytes()

Return the length of this type in bytes. Note that while the JDBC API _does_ define a need for returning length in bytes of a type, it doesn't state clearly what that means for the various types. We assume therefore that the values here are meant to match those specified by the ODBC specification (esp. since ODBC clients are more likely to need this value than a Java client). The ODBC spec that defines the values we use here can be found at the following link: http://msdn.microsoft.com/library/default.asp?url=/library/ en-us/odbc/htm/odbctransfer_octet_length.asp

Specified by:

getMaximumWidthInBytes in interface TypeDescriptor

Returns:

the maximum length of this Type IN BYTES; -1 means "unknown/no max length"

See Also:

TypeDescriptor.getMaximumWidthInBytes()

getJDBCTypeId

public int getJDBCTypeId()

Get the jdbc type id for this type. JDBC type can be found in java.sql.Types.

Specified by:

getJDBCTypeId in interface TypeDescriptor

Returns:

a jdbc type, e.g. java.sql.Types.DECIMAL

See Also:

Types

getTypeName

public java.lang.String getTypeName()

Gets the name of this datatype.

Specified by:

getTypeName in interface TypeDescriptor

Returns:

the name of this datatype

getPrecision

public int getPrecision()

Returns the number of decimal digits for the datatype, if applicable.

Specified by:

getPrecision in interface TypeDescriptor

Returns:

The number of decimal digits for the datatype. Returns zero for non-numeric datatypes.

getScale

public int getScale()

Returns the number of digits to the right of the decimal for the datatype, if applicable.

Specified by:

getScale in interface TypeDescriptor

Returns:

The number of digits to the right of the decimal for the datatype. Returns zero for non-numeric datatypes.

isNullable

public boolean isNullable()

Returns TRUE if the datatype can contain NULL, FALSE if not. JDBC supports a return value meaning "nullability unknown" - I assume we will never have columns where the nullability is unknown.

Specified by:

isNullable in interface TypeDescriptor

Returns:

TRUE if the datatype can contain NULL, FALSE if not.

setNullability

public void setNullability(boolean nullable)

Set the nullability of the datatype described by this descriptor

Parameters:

nullable - TRUE means set nullability to TRUE, FALSE means set it to FALSE

getSQLstring

public java.lang.String getSQLstring()

Converts this data type descriptor (including length/precision) to a string. E.g. VARCHAR(30) or java.util.Hashtable

Specified by:

getSQLstring in interface TypeDescriptor

Returns:

String version of datatype, suitable for running through the Parser.

toString

public java.lang.String toString()

getTypeId

public BaseTypeIdImpl getTypeId()

Get the type Id stored within this type descriptor.

equals

public boolean equals(java.lang.Object object)

Compare if two TypeDescriptors are exactly the same

Parameters:

object - the dataTypeDescriptor to compare to.

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Read this object from a stream of stored objects.

Specified by:

readExternal in interface java.io.Externalizable

Parameters:

in - read this.

Throws:

java.io.IOException - thrown on error

java.lang.ClassNotFoundException - thrown on error

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Write this object to a stream of stored objects.

Specified by:

writeExternal in interface java.io.Externalizable

Parameters:

out - write bytes here.

Throws:

java.io.IOException - thrown on error

getTypeFormatId

public int getTypeFormatId()

Get the formatID which corresponds to this class.

Specified by:

getTypeFormatId in interface TypedFormat

Returns:

the formatID of this class