public String first(String text) {
return text.substring(0, 1);
}
 
@EventHandler(priority = EventPriority.HIGHEST)
public void blockPlace(BlockPlaceEvent bpe)
{
    // Block placed by player
    Block block = bpe.getBlock();
 
    // Get the blocks material relative to the block placed by the player
    Material main = block.getType();
    Material up1 = block.getRelative(BlockFace.UP, 1).getType();
    Material up2 = block.getRelative(BlockFace.UP, 2).getType();
    Material down1 = block.getRelative(BlockFace.DOWN, 1).getType();
    Material down2 = block.getRelative(BlockFace.DOWN, 2).getType();
 
    // Concatenate the first letters of each of the materials
    String materialFirstLetters = first(up1.toString()) + first(up2.toString()) +
                                  first(main.toString()) + first(down1.toString()) +
                                  first(down2.toString());
 
    // Regex pattern
    String regex = "DIJ..|I.DJ.|..IDJ";
 
    // Check if the first letters of the materials match the regex pattern
    if (materialFirstLetters.matches(regex))
    {
        System.out.println("Antenna Created");
    }
}