NumberUtil.java

/*******************************************************************************
 * Signavio Core Components
 * Copyright (C) 2012  Signavio GmbH
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
package org.oryxeditor.server.diagram.util;


public class NumberUtil {

	/**
	 * Default maximum variation allowed for numbers to be considered as the same.
	 * Currently 1x10<sup>-6</sup>
	 */
	public static final double DEFAULT_DELTA = 1E-6;
	
	/**
	 * 
	 * @param num1
	 * @param num2
	 * @return true, if both numbers are within a minimal delta
	 * @see #DEFAULT_DELTA
	 */
	public static boolean areNumbersSame(Number num1, Number num2){
		return areNumbersWithinDelta(num1, num2, DEFAULT_DELTA);
	}
	
	
	/**
	 * 
	 * @param num1
	 * @param num2
	 * @param delta
	 * @return true, if num2 is within [num1-delta, num1+delta] (inclusive), false if either number is null
	 */
	public static boolean areNumbersWithinDelta(Number num1, Number num2, Double delta){
		if (num1 == null || num2 == null)
			return false;
		
		return 	(num1.doubleValue() <= num2.doubleValue()+delta) && 
				(num1.doubleValue() >= num2.doubleValue()-delta);
	}
	
	
	/**
	 * Parses a double from the given string, returns null if no double could be parsed.
	  * <p/>
	 * Handles "NaN" and Unicode infinity characters (returns negative or positive infinite depending on the leading sign)
	 * @param numberString
	 * @return double value or null
	 */
	public static Double createDouble(String numberString) {
		if (numberString == null)
			return null;
		else if (numberString.equals("NaN"))
			return Double.NaN;
		else if (numberString.equals("-\u221E"))
			return Double.NEGATIVE_INFINITY;
		else if (numberString.equals("\u221E"))
			return Double.POSITIVE_INFINITY;
		
		try{
			return Double.parseDouble(numberString);
		}catch(NumberFormatException e){
			return null;
		}
	}
	
	
	/**
	 * Parses a float from the given string, returns null if no float could be parsed.
	 * <p/>
	 * Handles "NaN" and Unicode infinity characters (returns negative or positive infinite depending on the leading sign)
	 * @param numberString
	 * @return float value or null
	 */
	public static Float createFloat(String numberString) {
		if (numberString == null)
			return null;
		else if (numberString.equals("NaN"))
			return Float.NaN;
		else if (numberString.equals("-\u221E"))
			return Float.NEGATIVE_INFINITY;
		else if (numberString.equals("\u221E"))
			return Float.POSITIVE_INFINITY;
		try{
			return Float.parseFloat(numberString);
		}catch(NumberFormatException e){
			return null;
		}
	}
	
	
	/**
	 * Parses a int from the given string, returns null if no int could be parsed.
	 * @param numberString
	 * @return int value or null
	 */
	public static Integer createInt(String numberString) {
		if (numberString == null)
			return null;

		try{
			return Integer.parseInt(numberString);
		}catch(NumberFormatException e){
			return null;
		}
	}
	
	
	/**
	 * Parses a long from the given string, returns null if no long could be parsed.
	 * @param numberString
	 * @return long value or null
	 */
	public static Long createLong(String numberString){
		if (numberString == null)
			return null;

		try{
			return Long.parseLong(numberString);
		}catch(NumberFormatException e){
			return null;
		}
	}
}