Class GenericResultDescription

java.lang.Object

org.apache.derby.impl.sql.GenericResultDescription

All Implemented Interfaces:

Externalizable, Serializable, Formatable, TypedFormat, ResultDescription

public final class GenericResultDescription
extends Object
implements ResultDescription, Formatable

GenericResultDescription: basic implementation of result description, used in conjunction with the other implementations in this package. This implementation of ResultDescription may be used by anyone.

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private Map<String,Integer>	columnNameMap	A map which maps a column name to a column number.
private ResultColumnDescriptor[]	columns	This class implements Formatable.
private ResultSetMetaData	metaData	Saved JDBC ResultSetMetaData object.
private String	statementType

Constructor Summary

Constructors

Constructor	Description
GenericResultDescription()	Niladic constructor for Formatable
GenericResultDescription(ResultColumnDescriptor[] columns, String statementType)	Build a GenericResultDescription from columns and type
GenericResultDescription(ResultDescription rd, int[] theCols)	Build a GenericResultDescription

Method Summary

Modifier and Type	Method	Description
int	findColumnInsenstive(String columnName)	Find a column name based upon the JDBC rules for getXXX and setXXX.
int	getColumnCount()	Returns the number of columns in the result set.
ResultColumnDescriptor	getColumnDescriptor(int position)	position is 1-based.
ResultColumnDescriptor[]	getColumnInfo()	Return information about all the columns.
ResultColumnDescriptor	getColumnInfo(int idx)	Return the information about a single column (0-based indexing)
ResultSetMetaData	getMetaData()	Get the saved meta data.
String	getStatementType()	Returns an identifier that tells what type of statement has been executed.
int	getTypeFormatId()	Get the formatID which corresponds to this class.
void	readExternal(ObjectInput in)	Read this object from a stream of stored objects.
void	setMetaData(ResultSetMetaData rsmd)	Set the meta data if it has not already been set.
String	toString()
ResultDescription	truncateColumns(int truncateFrom)	Get a new result description that has been truncated from input column number.
void	writeExternal(ObjectOutput out)	Write this object out

Methods inherited from class Object

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

Field Details

columns

private ResultColumnDescriptor[] columns

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.

statementType

private String statementType

metaData

private transient ResultSetMetaData metaData

Saved JDBC ResultSetMetaData object.

See Also:

• ResultDescription.setMetaData(java.sql.ResultSetMetaData)

columnNameMap

private Map<String,Integer> columnNameMap

A map which maps a column name to a column number. Entries only added when accessing columns with the name.

Constructor Details

GenericResultDescription

public GenericResultDescription()

Niladic constructor for Formatable

GenericResultDescription

public GenericResultDescription(ResultColumnDescriptor[] columns,
 String statementType)

Build a GenericResultDescription from columns and type

Parameters:

columns - an array of col descriptors

statementType - the type

GenericResultDescription

public GenericResultDescription(ResultDescription rd,
 int[] theCols)

Build a GenericResultDescription

Parameters:

rd - the result description

theCols - the columns to take from the input rd

Method Details

getStatementType

public String getStatementType()

Description copied from interface: ResultDescription

Returns an identifier that tells what type of statement has been executed. This can be used to determine what other methods to call to get the results back from a statement. For example, a SELECT statement returns rows and columns, while other statements don't, so you would only call getColumnCount() or getColumnType() for SELECT statements.

Specified by:

getStatementType in interface ResultDescription

Returns:

A String identifier telling what type of statement this is.

See Also:

• ResultDescription.getStatementType()

getColumnCount

public int getColumnCount()

Description copied from interface: ResultDescription

Returns the number of columns in the result set.

Specified by:

getColumnCount in interface ResultDescription

Returns:

The number of columns in the result set.

See Also:

• ResultDescription.getColumnCount()

getColumnInfo

public ResultColumnDescriptor[] getColumnInfo()

Description copied from interface: ResultDescription

Return information about all the columns.

Specified by:

getColumnInfo in interface ResultDescription

getColumnInfo

public ResultColumnDescriptor getColumnInfo(int idx)

Description copied from interface: ResultDescription

Return the information about a single column (0-based indexing)

Specified by:

getColumnInfo in interface ResultDescription

getColumnDescriptor

public ResultColumnDescriptor getColumnDescriptor(int position)

position is 1-based.

Specified by:

getColumnDescriptor in interface ResultDescription

Parameters:

position - The oridinal position of a column in the ResultSet.

Returns:

A ResultColumnDescriptor describing the column in the ResultSet.

See Also:

• ResultDescription.getColumnDescriptor(int)

truncateColumns

public ResultDescription truncateColumns(int truncateFrom)

Get a new result description that has been truncated from input column number. If the input column is 5, then columns 5 to getColumnCount() are removed. The new ResultDescription points to the same ColumnDescriptors (this method performs a shallow copy.

Specified by:

truncateColumns in interface ResultDescription

Parameters:

truncateFrom - the starting column to remove

Returns:

a new ResultDescription

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Write this object out

Specified by:

writeExternal in interface Externalizable

Parameters:

out - write bytes here

Throws:

IOException - thrown on error

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
ClassNotFoundException

Read this object from a stream of stored objects.

Specified by:

readExternal in interface Externalizable

Parameters:

in - read this.

Throws:

IOException - thrown on error

ClassNotFoundException - 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

toString

public String toString()

Overrides:

toString in class Object

setMetaData

public void setMetaData(ResultSetMetaData rsmd)

Set the meta data if it has not already been set.

Specified by:

setMetaData in interface ResultDescription

getMetaData

public ResultSetMetaData getMetaData()

Get the saved meta data.

Specified by:

getMetaData in interface ResultDescription

findColumnInsenstive

public int findColumnInsenstive(String columnName)

Find a column name based upon the JDBC rules for getXXX and setXXX. Name matching is case-insensitive, matching the first name (1-based) if there are multiple columns that map to the same name.

Specified by:

findColumnInsenstive in interface ResultDescription

Parameters:

columnName -

Returns:

Position of the column (1-based), -1 if no match.