javax.units
Class BaseUnit

java.lang.Object
  javax.units.Unit
      javax.units.BaseUnit

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

Currency

public class BaseUnit

extends Unit

This class represents the building blocks on top of which all others units are created.

By default, base units are mutually independent. Although, in specialized context (e.g. relativistic context), conversions between base units is possible (Ref. setDimension(javax.units.Unit, javax.units.Converter)).

Examples of base units:

         METER = BaseUnit.getInstance("m");
         KILOGRAM = BaseUnit.getInstance("kg");
         SECOND = BaseUnit.getInstance("s");
         AMPERE = BaseUnit.getInstance("A");
     

Version:

4.0, January 30, 2003

Author:

Jean-Marie Dautelle

See Also:

Serialized Form

Field Summary

Fields inherited from class javax.units.Unit

ONE

Constructor Summary

protected

BaseUnit(java.lang.String symbol) Creates a base unit with the specified symbol.

Method Summary

boolean	equals(java.lang.Object that) Indicates if this unit is equal to the object specified.
static BaseUnit	getInstance(java.lang.String symbol) Returns the base unit with the specified symbol.
java.lang.String	getSymbol() Returns the symbol for this base unit.
Unit	getSystemUnit() Returns the system unit for this unit.
void	setDimension(Unit dimension, Converter toDimension) Sets the dimension of this base unit (context-local).

Methods inherited from class javax.units.Unit

add, alternate, appendTo, divide, getConverterTo, getDimension, getInstance, getInstances, hashCode, isCompatible, isSystemUnit, multiply, multiply, pow, readResolve, root, searchSymbol, toString, valueOf

Methods inherited from class java.lang.Object

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

Constructor Detail

BaseUnit

protected BaseUnit(java.lang.String symbol)

Creates a base unit with the specified symbol.

Parameters:

symbol - the symbol of this base unit.

Method Detail

getInstance

public static BaseUnit getInstance(java.lang.String symbol)

Returns the base unit with the specified symbol. If the base unit does not already exist, then it is created.

Parameters:

symbol - the base unit symbol.

Returns:

the corresponding base unit.

Throws:

java.lang.IllegalArgumentException - if the specified symbol is currently associated to a different type of unit.

getSymbol

public final java.lang.String getSymbol()

Returns the symbol for this base unit.

Returns:

this base unit's symbol.

setDimension

public void setDimension(Unit dimension,
                         Converter toDimension)

Sets the dimension of this base unit (context-local). By default a base unit's dimension is itself. It is possible to set the dimension to any other unit. The only constraint being that distinct dimensional units should be independent from each other (e.g. if the dimensional unit for meter is "ns", then the dimensional unit for second should be "ns" as well). For example:

 LocalContext.enter(); // Ensures that setting is local to current thread.
 try {
     SI.METER.setDimension(SI.NANO(SI.SECOND),
                           new MultiplyConverter(1e9 / c));
     SI.SECOND.setDimension(SI.NANO(SI.SECOND),
                            new MultiplyConverter(1e9));
     // In this high-energy context, length and time are compatible,
     // they have the same "ns" dimensional unit.
 } finally {
     LocalContext.exit();
 }

Parameters:

dimension - the unit identifying the new dimension of this base unit.

toDimension - the converter to the specified dimensional unit.

See Also:

LocalContext

getSystemUnit

public Unit getSystemUnit()

Description copied from class: Unit

Returns the system unit for this unit. The system unit identifies the nature of the quantity being measured using this unit.

Note: Having the same system units is not sufficient to ensure that a converter exists between the two units (e.g. °C/m and K/m).

Specified by:

getSystemUnit in class Unit

Returns:

the system unit for this unit.

See Also:

Unit.isSystemUnit()

equals

public boolean equals(java.lang.Object that)

Description copied from class: Unit

Indicates if this unit is equal to the object specified. Units are unique and immutable, therefore users might want to use == to test for equality.

Specified by:

equals in class Unit

Parameters:

that - the object to compare for equality.

Returns:

true if this unit and the specified object are considered equal; false otherwise.