make bukkit plugin

I want to make a laser gun.
I tried to make it for trial but it didn't work well.
Please tell me what to do.

Code:

package r.test;

import org.bukkit.*;
import org.bukkit.entity.Entity;
import org.bukkit.entity.LivingEntity;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.Action;
import org.bukkit.event.player.PlayerInteractEvent;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;
import org.bukkit.util.Vector;

public final class Test extends JavaPlugin implements Listener {




    @EventHandler
    public void effect2(PlayerInteractEvent event){
        if(event.getAction()== Action.RIGHT_CLICK_AIR){
            if(event.getItem().getItemMeta().getDisplayName().equalsIgnoreCase("boom 1")){
                final Player player = event.getPlayer();
                Location lo = player.getLocation();
                final Location loc = lo.add(0,1.5,0);
                new BukkitRunnable(){
                    double t = 0;
                    Vector di =loc.getDirection().normalize();
                    public void run(){
                        t = t + 0.5;
                        double x = di.getX() * t;
                        double y = di.getY() * t;
                        double z = di.getZ() * t;
                        loc.add(x,y,z);
                        event.getPlayer().getWorld().spawnParticle(Particle.FIREWORKS_SPARK,loc,1,0,0,0,0);
                        loc.subtract(x,y,z);


                        for(Entity e : loc.getWorld().getEntities())
                            if (e instanceof LivingEntity) {
                                if(loc.getBlock()==e.getLocation().getBlock()){}
                                player.sendMessage("a");
                                double damage = 4.0;
                                ((LivingEntity) e).damage(damage);
                            }

                        }

                        if(t>30){
                            this.cancel();
                        }
                    }
                }.runTaskTimerAsynchronously(this,0,0);
            }
        }
    }
}