How get block side which one is looking player

[Intezium]

The image posted is the general idea of what I am trying to say..

[warjort]

It depends where you are in the code and what kind of raycast/HitResult you find acceptable.

If your HitResult is hitting a block you will have a BlockHitResult which has a getSide().

Assuming where you are in the code doesn't have a HitResult parameter:

On the client there is MinecraftClient.crosshairTarget which may or may not be a BlockHitResult
See MinecraftClient.doItemUse() for example.

You can do the calculation from scratch using something like:

		HitResult hit = entity.raycast(20, 0, false); // 20 is distance used by the DebugHud for "looking at block", false means ignore fluids
		if (hit.getType() == HitResult.Type.BLOCK) {
			BlockHitResult blockHit = (BlockHitResult) hit;
			if (blockHit.getSide() == whatever) {
				// do stuff
			}
		}

On the client the entity would be MinecraftClient.cameraEntity or on the server you would use the ServerPlayerEntity.

[SplashAni]

You can simply use
BlockHitResult bhr = new BlockHitResult(Vec3d.of(pos),mc.player.getHorizontalFacing(),pos,false);