### Question:
EndianUtils { public static double swapDouble(final double value) { return Double.longBitsToDouble( swapLong( Double.doubleToLongBits( value ) ) ); } EndianUtils(); static short swapShort(final short value); static int swapInteger(final int value); static long swapLong(final long value); static float swapFloat(final float value); static double swapDouble(final double value); static void writeSwappedShort(final byte[] data, final int offset, final short value); static short readSwappedShort(final byte[] data, final int offset); static int readSwappedUnsignedShort(final byte[] data, final int offset); static void writeSwappedInteger(final byte[] data, final int offset, final int value); static int readSwappedInteger(final byte[] data, final int offset); static long readSwappedUnsignedInteger(final byte[] data, final int offset); static void writeSwappedLong(final byte[] data, final int offset, final long value); static long readSwappedLong(final byte[] data, final int offset); static void writeSwappedFloat(final byte[] data, final int offset, final float value); static float readSwappedFloat(final byte[] data, final int offset); static void writeSwappedDouble(final byte[] data, final int offset, final double value); static double readSwappedDouble(final byte[] data, final int offset); static void writeSwappedShort(final OutputStream output, final short value); static short readSwappedShort(final InputStream input); static int readSwappedUnsignedShort(final InputStream input); static void writeSwappedInteger(final OutputStream output, final int value); static int readSwappedInteger(final InputStream input); static long readSwappedUnsignedInteger(final InputStream input); static void writeSwappedLong(final OutputStream output, final long value); static long readSwappedLong(final InputStream input); static void writeSwappedFloat(final OutputStream output, final float value); static float readSwappedFloat(final InputStream input); static void writeSwappedDouble(final OutputStream output, final double value); static double readSwappedDouble(final InputStream input);  }### Answer:
@Test public void testSwapDouble() { assertEquals( 0.0, EndianUtils.swapDouble( 0.0 ), 0.0 ); final double d1 = Double.longBitsToDouble( 0x0102030405060708L ); final double d2 = Double.longBitsToDouble( 0x0807060504030201L ); assertEquals( d2, EndianUtils.swapDouble( d1 ), 0.0 ); }