@NullUnmarked
public class DoubleUtilsTest extends TestCase {
  @AndroidIncompatible // no FpUtils and no Math.nextDown in old versions
  public void testNextDown() throws Exception {
    Method jdkNextDown = getJdkNextDown();
    for (double d : FINITE_DOUBLE_CANDIDATES) {
      assertEquals(jdkNextDown.invoke(null, d), DoubleUtils.nextDown(d));
    }
  }

  private static Method getJdkNextDown() throws Exception {
    try {

            ? roundArbitrarily
            : DoubleUtils.nextDown(roundArbitrarily);
      case CEILING:
        return (cmpXToRoundArbitrarily <= 0) ? roundArbitrarily : Math.nextUp(roundArbitrarily);
      case DOWN:
        if (sign(x) >= 0) {
          return (cmpXToRoundArbitrarily >= 0)
              ? roundArbitrarily
              : DoubleUtils.nextDown(roundArbitrarily);
        } else {

import java.math.BigInteger;

/**
 * Utilities for {@code double} primitives.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
final class DoubleUtils {
  private DoubleUtils() {}

  static double nextDown(double d) {
    return -Math.nextUp(-d);
  }

  // The mask for the significand, according to the {@link
  // Double#doubleToRawLongBits(double)} spec.
  static final long SIGNIFICAND_MASK = 0x000fffffffffffffL;

import java.math.BigInteger;

/**
 * Utilities for {@code double} primitives.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
final class DoubleUtils {
  private DoubleUtils() {}

  static double nextDown(double d) {
    return -Math.nextUp(-d);
  }

  // The mask for the significand, according to the {@link
  // Double#doubleToRawLongBits(double)} spec.
  static final long SIGNIFICAND_MASK = 0x000fffffffffffffL;