Guava Range Utilities (Java 8)

GuavaRangeUtils.java

import com.google.common.collect.Range;
import java.util.function.Function;

public class GuavaRangeUtils {

  public static <T extends Comparable<?>, S extends Comparable<?>> Range<S> transformRange(Range<T> range, Function<T, S> transformer) {
        if (range == null) {
            return null;
        }
        if (range.hasLowerBound()) {
            S lower = transformer.apply(range.lowerEndpoint());
            if (range.hasUpperBound()) {
                S upper = transformer.apply(range.upperEndpoint());
                return Range.range(lower, range.lowerBoundType(), upper, range.upperBoundType());
            } else {
                return Range.downTo(lower, range.lowerBoundType());
            }
        } else if (range.hasUpperBound()) {
            S upper = transformer.apply(range.upperEndpoint());
            return Range.upTo(upper, range.upperBoundType());
        } else {
            return Range.all();
        }
    }

}