i want to add a trident at player position but nothing happen.

    @SubscribeEvent
    public void onClientTickEvent(final TickEvent.ClientTickEvent event)
    {
        if(event.phase != TickEvent.Phase.END) return;
        Minecraft minecraft = Minecraft.getInstance();
        if(minecraft.player == null) return;
        PlayerEntity player = minecraft.player;
        ItemStack mainHand = player.getHeldItemMainhand();
        if(KeyBindingHandler.throw_saber.isPressed() && mainHand.getItem() instanceof BeamSaber)
        {
            TridentEntity trident = new TridentEntity(minecraft.world,player,mainHand);
            minecraft.world.addEntity(trident);
        }
    }

 

You can't add an entity from the client, you have to use another event, for instance the PlayerTickEvent.