org.jcamp.units.Unit Maven / Gradle / Ivy
package org.jcamp.units;
import java.io.Serializable;
/**
* abstract base class for units.
*
* @author Thomas Weber
*/
public abstract class Unit
implements Cloneable, Serializable {
/** for serialization. */
private static final long serialVersionUID = -6839485344921903829L;
private static java.util.Hashtable idMap = new java.util.Hashtable();
private static java.util.Hashtable aliasMap = new java.util.Hashtable();
private final String identifier;
static {
initHashtables();
}
/**
* create unit with identifier identifier
* @param identifier String
*/
protected Unit(String identifier) {
super();
if (identifier != null && identifier.length() > 0)
identifier.replace(' ', '_');
this.identifier = identifier.toUpperCase();
Unit.idMap.put(this.identifier, this);
}
/**
* create unit with identifier identifier
* @param identifier String
*/
protected Unit(String identifier, String alias) {
super();
if (identifier != null && identifier.length() > 0)
identifier.replace(' ', '_');
this.identifier = identifier.toUpperCase();
Unit.idMap.put(this.identifier, this);
addAlias(this, alias);
}
/**
* add alias for unit dictionary.
* @param unit Unit
* @param alias java.lang.String
*/
public static void addAlias(Unit unit, String alias) {
if (alias != null && alias.length() > 0) {
String key = alias.toUpperCase();
key.replace(' ', '_');
if (Unit.aliasMap.get(key) == null) {
Unit.aliasMap.put(key, unit);
}
}
}
/**
* cloning.
*
* @return java.lang.Object
*/
@Override
public Object clone() {
Unit unit = null;
try {
unit = (Unit) super.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
return unit;
}
/**
* convert double value from thatUnit
* into this unit. returns converted value.
* @return double
* @param value double
* @param thatUnit Unit
*/
public abstract double convertFrom(double value, Unit thatUnit) throws UnitException;
/**
* convert double value given in this unit
* into thatUnit
* returns converted value.
* @return double
* @param value double
* @param thatUnit Unit
*/
public abstract double convertTo(double value, Unit thatUnit) throws UnitException;
/**
* compare units, if they have the same key and describe the same quantity they are considered equal.
* @return boolean
* @param obj java.lang.Object
*/
@Override
public boolean equals(Object obj) {
if (obj instanceof Unit) {
Unit unit = (Unit) obj;
if (unit.getIdentifier().equals(this.identifier))
return true;
}
return false;
}
/**
* strip any SI-prefix and try to find BaseUnit
* @return Unit
* @param id java.lang.String
*/
static Unit getBaseUnitFromKey(String id) {
int n = SIUnitScale.prefixes.length;
Unit unit;
for (int i = 0; i < n; i++) {
String prefix = SIUnitScale.prefixes[i].getName().toUpperCase();
if (id.startsWith(prefix)) {
unit = Unit.getUnitFromKey(id.substring(prefix.length()));
if (unit != null)
return new ScaledUnit(unit, SIUnitScale.prefixes[i]);
}
prefix = SIUnitScale.prefixes[i].getPrefix().toUpperCase();
if (id.startsWith(prefix)) {
unit = Unit.getUnitFromKey(id.substring(prefix.length()));
if (unit != null)
return new ScaledUnit(unit, SIUnitScale.prefixes[i]);
}
}
return null;
}
/**
* gets unit identifier (e.g. unit symbol).
* @return java.lang.String
*/
final String getIdentifier() {
return identifier;
}
/**
* gets unit definition (long name).
* @return java.lang.String
*/
public abstract String getName();
/**
* gets quantity measured by this unit.
* @return java.lang.String
*/
public abstract String getQuantity();
/**
* gets scale factor.
* @return double
*/
abstract double getScaleFactor();
/**
* gets unit symbol.
* @return java.lang.String
*/
public abstract String getSymbol();
/**
* get unit from unit key.
* @return Unit
* @param key java.lang.String
*/
static Unit getUnitFromKey(String key) {
// direct test
Unit unit = (Unit) (Unit.idMap.get(key));
// alias test
if (unit == null) {
unit = (Unit) (Unit.aliasMap.get(key));
}
return unit;
}
/**
* get unit from unit string.
* @return Unit
* @param id java.lang.String
*/
public static Unit getUnitFromString(String id) {
String key = id.toUpperCase();
Unit unit = getUnitFromKey(key);
// scaled unit
if (unit == null) {
unit = getBaseUnitFromKey(key);
}
if (unit == null) { // plural s?
if (key.endsWith("ES") && key.length() > 5) {
String skey = key.substring(0, key.length() - 2);
unit = getUnitFromKey(skey);
if (unit == null) { // plural s?
unit = getBaseUnitFromKey(skey);
}
}
if (unit == null && (key.endsWith("S") && key.length() > 4)) {
String skey = key.substring(0, key.length() - 1);
unit = getUnitFromKey(skey);
if (unit == null) { // plural s?
unit = getBaseUnitFromKey(skey);
}
}
}
if (unit == null) {
return new AliasUnit(CommonUnit.generic, id);
} else
return unit;
}
/**
* get hashcode.
*
* @return int
*/
@Override
public int hashCode() {
return identifier.hashCode();
}
/**
* initialize Hashtables.
*
*/
private static void initHashtables() {
try {
Class.forName("org.jcamp.units.BaseUnit");
Class.forName("org.jcamp.units.CommonUnit");
} catch (ClassNotFoundException e) {
System.err.println("predefined units not available");
}
}
/**
* check if thatUnit is convertible into
* this unit.
* @return boolean
* @param unit Unit
*/
public abstract boolean isConvertibleTo(Unit thatUnit);
/**
* gets String representation.
* @return java.lang.String
*/
@Override
public final String toString() {
String s = getSymbol();
if (s == null || s.length() == 0)
s = getName();
if (s == null || s.length() == 0)
s = getIdentifier();
return s;
}
}