com.klg.jclass.datasource
Class BaseVirtualColumn

java.lang.Object
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  +--com.klg.jclass.datasource.BaseColumn
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        +--com.klg.jclass.datasource.BaseVirtualColumn

All Implemented Interfaces:

ColumnModel, Serializable, VirtualColumnModel

public class BaseVirtualColumn

extends BaseColumn

implements VirtualColumnModel

Adds columns to rows which are not retrieved from the data source. This class allows you to add columns which are derived by performing an operation on one or more other columns in the row to arrive at a new value.

The basic supported operations are:

• MIN
• MAX
• AVERAGE
• SUM
• PRODUCT
• QUOTIENT
• DIFFERENCE

Operations can be performed on one or more columns. Columns are evaluated from left to right. Virutal columns can be used in calculations for other virtual columns in the row.

See Also:

Serialized Form

Field Summary

static int	AVERAGE
protected String[]	columns
static int	DIFFERENCE
static int	MAX
static int	MIN
protected int	operation
static int	PRODUCT
static int	QUOTIENT
protected int	roundMode
protected int	scale
static int	SUM

Fields inherited from class com.klg.jclass.datasource.BaseColumn

catalog, columnClassName, displayWidth, identifier, isAutoIncrement, isCaseSensitive, isCurrency, isDefinitelyWritable, isNullable, isReadOnly, isSearchable, isSigned, isWritable, label, metaType, name, NOT_SET, precision, schema, table, type, typeName

Constructor Summary

BaseVirtualColumn(String name, int type, int operation, String[] columns)
Creates a column which is calculated based on one or more data source columns.

Method Summary

String[]	getColumns() Returns the list of names of the columns used to derive the virtual column.
int	getOperation() Returns the operation.
Object	getResultData(com.klg.jclass.datasource.DataTableModel dtm, long bookmark) Returns the value calculated by performing operation on columns .
int	getRoundMode() Returns the roundMode.
int	getScale(int scale) Returns the scale which is used when dividing.
boolean	isReadOnly()
void	setReadOnly(boolean isReadOnly)
void	setRoundMode(int roundMode) Sets the roundMode to be used when dividing.
void	setScale(int scale) Sets the scale to be used when dividing.

Methods inherited from class com.klg.jclass.datasource.BaseColumn

getCatalogName, getColumnClassName, getColumnDisplaySize, getColumnLabel, getColumnName, getColumnType, getColumnTypeName, getIdentifier, getMetaColumnType, getPrecision, getScale, getSchemaName, getTableName, isAutoIncrement, isCaseSensitive, isCurrency, isDefinitelyWritable, isNullable, isSearchable, isSigned, isTimeDate, isWritable, setAutoIncrement, setCaseSensitive, setCatalogName, setColumnClassName, setColumnDisplaySize, setColumnLabel, setColumnName, setColumnType, setColumnTypeName, setCurrency, setDefinitelyWritable, setIdentifier, setMetaColumnType, setMetaColumnTypeFromSqlType, setNullable, setPrecision, setSchemaName, setSearchable, setSigned, setTableName, setWritable

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.klg.jclass.datasource.ColumnModel

getCatalogName, getColumnClassName, getColumnDisplaySize, getColumnLabel, getColumnName, getColumnType, getColumnTypeName, getIdentifier, getMetaColumnType, getPrecision, getScale, getSchemaName, getTableName, isAutoIncrement, isCaseSensitive, isCurrency, isDefinitelyWritable, isNullable, isSearchable, isSigned, isTimeDate, isWritable, setAutoIncrement, setCaseSensitive, setCatalogName, setColumnClassName, setColumnDisplaySize, setColumnLabel, setColumnName, setColumnType, setColumnTypeName, setCurrency, setDefinitelyWritable, setIdentifier, setMetaColumnType, setMetaColumnTypeFromSqlType, setNullable, setPrecision, setSchemaName, setSearchable, setSigned, setTableName, setWritable

Field Detail

MIN

public static final int MIN

See Also:

Constant Field Values

MAX

public static final int MAX

See Also:

Constant Field Values

AVERAGE

public static final int AVERAGE

See Also:

Constant Field Values

SUM

public static final int SUM

See Also:

Constant Field Values

DIFFERENCE

public static final int DIFFERENCE

See Also:

Constant Field Values

PRODUCT

public static final int PRODUCT

See Also:

Constant Field Values

QUOTIENT

public static final int QUOTIENT

See Also:

Constant Field Values

operation

protected int operation

columns

protected String[] columns

scale

protected int scale

roundMode

protected int roundMode

Constructor Detail

BaseVirtualColumn

public BaseVirtualColumn(String name,
                         int type,
                         int operation,
                         String[] columns)

Creates a column which is calculated based on one or more data source columns. For example,

     String name = "difference";
     int type = java.sql.Types.INTEGER;
     int operation = BaseVirtualColumn.DIFFERENCE;
     String columns[] = {"colA", "colB", "colC"}
     BaseVirtualColumn bvc = new BaseVirtualColumn(name, type, operation, columns);
 

This example is equivalent to the difference calculation colA - colB - colC.

Parameters:

name - the String name of the column to be displayed.

type - the java.sql.Types type of the column, will be automatically mapped to a MetaDataModel type.

operation - an int constant one of MIN, MAX, AVERAGE, SUM, PRODUCT, QUOTIENT, DIFFERENCE.

columns - an array of column identifiers indicating which columns to use in the operation.

Method Detail

getResultData

public Object getResultData(com.klg.jclass.datasource.DataTableModel dtm,
                            long bookmark)
                     throws DataModelException

Returns the value calculated by performing operation on columns .

Specified by:

getResultData in interface VirtualColumnModel

Parameters:

bookmark - a long which uniquely identifies a row.

Returns:

the value calculated by performing operation on columns.

Throws:

DataModelException - If the operation fails.

setScale

public void setScale(int scale)

Sets the scale to be used when dividing. The default value is 5.

Specified by:

setScale in interface ColumnModel

Overrides:

setScale in class BaseColumn

Parameters:

scale - an int which indicates the scale.

See Also:

getScale(int), BigDecimal

getScale

public int getScale(int scale)

Returns the scale which is used when dividing. The default value is 5.

Returns:

the scale.

See Also:

setScale(int), BigDecimal

setRoundMode

public void setRoundMode(int roundMode)

Sets the roundMode to be used when dividing. The default mode is BigDecimal.ROUND_CEILING.

Parameters:

roundMode - an int on of the java.math.BigDecimal roundMode constants.

See Also:

BigDecimal

getRoundMode

public int getRoundMode()

Returns the roundMode. The default mode is BigDecimal.ROUND_CEILING.

Returns:

the method used to round numbers when dividing.

See Also:

BigDecimal

getOperation

public int getOperation()

Returns the operation.

Returns:

the operation to be performed, one of

• MIN
• MAX
• AVERAGE
• SUM
• PRODUCT
• QUOTIENT
• DIFFERENCE

getColumns

public String[] getColumns()

Returns the list of names of the columns used to derive the virtual column.

Returns:

a String[] array of the column names.

isReadOnly

public boolean isReadOnly()

Specified by:

isReadOnly in interface ColumnModel

Overrides:

isReadOnly in class BaseColumn

setReadOnly

public void setReadOnly(boolean isReadOnly)

Specified by:

setReadOnly in interface ColumnModel

Overrides:

setReadOnly in class BaseColumn