### Question:
ArrayUtils { public static float[] convertDoublesToFloats(double[] input, float[] output) { if (input == null || output == null) return output; for (int i = 0; i < input.length; ++i) { output[i] = (float) input[i]; } return output; }  static float[] convertDoublesToFloats(double[] input, float[] output); static float[] convertDoublesToFloats(double[] input); static double[] convertFloatsToDoubles(float[] input, double[] output); static double[] convertFloatsToDoubles(float[] input); static double[] concatAllDouble(double[] ... arrays); static float[] concatAllFloat(float[] ... arrays); static int[] concatAllInt(int[] ... arrays); static double[] getDoubleArrayFromBuffer(DoubleBuffer buffer); static float[] getFloatArrayFromBuffer(FloatBuffer buffer); static int[] getIntArrayFromBuffer(Buffer buffer);  }### Answer:
@Test public void testConvertDoublesToFloats() { double[] input = null; float[] output = null; assertNull(ArrayUtils.convertDoublesToFloats(input, output)); assertNull(ArrayUtils.convertDoublesToFloats(input)); }