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Generic Evolver utility classes
There is a newer version: 3.5.0
package fi.evolver.utils;

import java.util.Comparator;

public class NullSafetyUtils {

	private NullSafetyUtils() {
		throw new IllegalStateException("Util class");
	}

	public static > int nullSafeCompare(T value1, T value2, boolean smallNull) {
		if (value1 == null)
			return value2 == null ? 0 : (smallNull ? -1 : 1);
		if (value2 == null)
			return smallNull ? 1 : -1;
		return value1.compareTo(value2);
	}

	public static > int nullSafeCompare(T value1, T value2) {
		return nullSafeCompare(value1, value2, true);
	}


	@SafeVarargs
	public static  T denull(T... values) {
		for (T value: values) {
			if (value != null)
				return value;
		}
		return null;
	}

	/**
	 * Null safe comparator implementation.
	 * Tests arguments for null and calls argument comparator if both are non-null.
	 *
	 * @param  The type to compare
	 */
	public static class NullSafeComparator implements Comparator {
		private Comparator realComparator;
		private boolean smallNull = true;

		public NullSafeComparator(Comparator comparator) {
			this.realComparator = comparator;
		}

		public NullSafeComparator(Comparator comparator, boolean smallNull) {
			this.realComparator = comparator;
			this.smallNull = smallNull;
		}

		@Override
		public int compare(T o1, T o2) {
			return nullCompare(o1, o2, realComparator, smallNull);
		}

	}

	/**
	 * Null safe compareTo method. Calls nonNullComparator iff neither argument to compare is null.
	 *
	 * @param value1 The first value to compare
	 * @param value2 The second value to compare
	 * @param nonNullComparator The comparator to call in case both values are not null
	 * @return -1, 1 or 0
	 */
	public static  int nullCompare(T value1, T value2, Comparator nonNullComparator) {
		return nullCompare(value1, value2, nonNullComparator, true);
	}

	/**
	 * Null safe compareTo method. Calls nonNullComparator iff neither argument to compare is null.
	 *
	 * @param value1 The first value to compare
	 * @param value2 The second value to compare
	 * @param nonNullComparator The comparator to call in case both values are not null
	 * @param smallNull true if null is smaller than non-null
	 * @return -1, 1 or 0
	 */
	public static  int nullCompare(T value1, T value2, Comparator nonNullComparator, boolean smallNull) {
		if (value1 == null)
			return value2 == null ? 0 : (smallNull ? -1 : 1);
		if (value2 == null)
			return smallNull ? 1 : -1;
		return nonNullComparator.compare(value1, value2);
	}

}