@Test
  public void testForEachKey() {
    final DoubleArrayList keys = new DoubleArrayList();
    OpenDoubleObjectHashMap<TestClass> map = new OpenDoubleObjectHashMap<TestClass>();
    map.put((double) 11, anotherItem);
    map.put((double) 12, anotherItem2);
    map.put((double) 13, anotherItem3);
    map.put((double) 14, anotherItem4);
    map.removeKey((double) 13);
    map.forEachKey(
        new DoubleProcedure() {

          @Override
          public boolean apply(double element) {
            keys.add(element);
            return true;
          }
        });

    double[] keysArray = keys.toArray(new double[keys.size()]);
    Arrays.sort(keysArray);

    assertArrayEquals(new double[] {11, 12, 14}, keysArray, (double) 0.000001);
  }