Ladder

You don't want the ladder but the block it is resting on, correct?

 

I have found this:
Ladder ladder = (Ladder)world.getBlockAt(x, y, z).getState().getData();

 

Would be similar to this:

Code (Text):

Block oppositeBlock = ladderBlock.getRelative(ladderBlock.getFace(ladderBlock).getOppositeFace());
 

 

To be correct, this is how you do it

Code (Text):

Ladder ladder = (Ladder) ladderBlock.getState().getData();
Block oppositeBlock = ladderBlock.getRelative(ladder.getFacing().getOppositeFace());