QuantityUtils.java

package org.goko.core.common.measure.quantity;

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.util.Locale;

import org.apache.commons.lang3.StringUtils;
import org.goko.core.common.measure.units.Unit;

public final class QuantityUtils {
		
	/**
	 * Performs the addition of the two given quantity and make sure the type of quantity remains the same 
	 * Unit conversion is used to make sure the sum is made in the corresponding units
	 * @param a quantity A
	 * @param b quantity B
	 * @return the sum of the two values 
	 */
	public static <Q extends Quantity<Q>> Q add(Q a, Q b){
		if(a == null){
			return b;
		}else if(b == null){
			return a;
		}
		return a.add(b);
	}
		
	/**
	 * Performs the subtraction of the two given quantity and make sure the type of quantity remains the same 
	 * Unit conversion is used to make sure the sum is made in the corresponding units
	 * @param a quantity A
	 * @param b quantity B
	 * @return the subtraction of the two values 
	 */
	public static <Q extends Quantity<Q>> Q subtract(Q a, Q b){
		if(a == null){
			return b;
		}else if(b == null){
			return a;
		}
		return a.subtract(b);
	}
	
	/**
	 * Performs the multiplication of the given quantity and the given factor and make sure the type of quantity remains the same 
	 * Unit conversion is used to make sure the sum is made in the corresponding units
	 * @param a quantity A
	 * @param factor multiply factor
	 * @return the sum of the two values 
	 */
	public static <Q extends Quantity<Q>> Q multiply(Q a, int factor){
		if(a == null){
			return null;
		}
		return a.multiply(factor);
	}
	
	/**
	 * Returns the minimum quantity between the 2 given Quantity. Unit conversion
	 * is used to make sure the comparison is made in the corresponding units
	 * @param a quantity A
	 * @param b quantity B
	 * @return the quantity representing the lowest amount 
	 */
	public static <Q extends Quantity<Q>> Q min(Q a, Q b){
		if(a == null){
			return b;
		}else if(b == null){
			return a;
		}
		if(a.value(b.getUnit()).compareTo(b.value(b.getUnit())) < 0){
			return a;
		}
		return b;
	}
	
	/**
	 * Returns the maximum quantity between the 2 given Quantity. Unit conversion
	 * is used to make sure the comparison is made in the corresponding units
	 * @param a quantity A
	 * @param b quantity B
	 * @return the quantity representing the lowest amount 
	 */
	public static <Q extends Quantity<Q>> Q max(Q a, Q b){
		if(a == null){
			return b;
		}else if(b == null){
			return a;
		}
		if(a.value(b.getUnit()).compareTo(b.value(b.getUnit())) > 0){
			return a;
		}
		return b;
	}
	
	public static <Q extends Quantity<Q>> String format(Q quantity){
		return format(quantity, null, false, false, quantity.getUnit());
	}
	
	public static <Q extends Quantity<Q>> String format(Q quantity, Integer digitCount){
		return format(quantity, digitCount, false, false, quantity.getUnit());
	}
	
	public static <Q extends Quantity<Q>> String format(Q quantity, Integer digitCount, boolean keepTraillingZero){
		return format(quantity, digitCount, keepTraillingZero, false, quantity.getUnit());
	}
	
	public static <Q extends Quantity<Q>> String format(Q quantity, Integer digitCount, boolean keepTraillingZero, boolean displayUnit){
		return format(quantity, digitCount, keepTraillingZero, displayUnit, quantity.getUnit());
	}
	
	public static <Q extends Quantity<Q>> String format(Q quantity, Integer digitCount, boolean keepTraillingZero, boolean displayUnit, Unit<Q> ptargetUnit){
		String result = StringUtils.EMPTY;
		Unit<Q> 	localTargetUnit 	= ptargetUnit;
				
		DecimalFormat df = new DecimalFormat("0", DecimalFormatSymbols.getInstance(Locale.ENGLISH));
		
		if(digitCount != null){			
			df.setMaximumFractionDigits(digitCount);
			if(keepTraillingZero){
				df.setMinimumFractionDigits(digitCount);
			}
		}else{
			df.setMaximumFractionDigits(10);
			df.setMinimumFractionDigits(0);
		}
		result = df.format(quantity.doubleValue(localTargetUnit));
		
		if(displayUnit){
			result += ptargetUnit.getSymbol();
		}
		return result;
	}
}