How to use

filter

method

in

org.apache.druid.java.util.common.guava.FunctionalIterable

private Iterable<BytesMessageWithOffset> filterAndDecode(Iterable<MessageAndOffset> kafkaMessages, final long offset)
{
 return FunctionalIterable
   .create(kafkaMessages)
   .filter(
     new Predicate<MessageAndOffset>()
     {
      @Override
      public boolean apply(MessageAndOffset msgAndOffset)
      {
       return msgAndOffset.offset() >= offset;
      }
     }
   )
   .transform(
     new Function<MessageAndOffset, BytesMessageWithOffset>()
     {
      @Override
      public BytesMessageWithOffset apply(MessageAndOffset msgAndOffset)
      {
       ByteBuffer bb = msgAndOffset.message().payload();
       byte[] payload = new byte[bb.remaining()];
       bb.get(payload);
       // add nextOffset here, thus next fetch will use nextOffset instead of current offset
       return new BytesMessageWithOffset(payload, msgAndOffset.nextOffset(), partitionId);
      }
     }
   );
}

@Test
public void testFilter()
{
 Assert.assertEquals(
   Lists.newArrayList(
     FunctionalIterable.create(Arrays.asList("1", "2", "3"))
              .filter(
                new Predicate<String>()
                {
                 @Override
                 public boolean apply(String input)
                 {
                  return !"2".equals(input);
                 }
                }
              )
   ),
   Arrays.asList("1", "3")
 );
}