jumlah barang di inventory

#==============================================================================
# ** Scene_Shop
#------------------------------------------------------------------------------
#  This class performs shop screen processing.
#==============================================================================

class Scene_Shop < Scene_Base
  #--------------------------------------------------------------------------
  # * Update Buy Item Selection
  #--------------------------------------------------------------------------
  def update_buy_selection
    @status_window.item = @buy_window.item
    if Input.trigger?(Input::B)
      Sound.play_cancel
      @command_window.active = true
      @dummy_window.visible = true
      @buy_window.active = false
      @buy_window.visible = false
      @status_window.visible = false
      @status_window.item = nil
      @help_window.set_text("")
      return
    end
    if Input.trigger?(Input::C)
      @item = @buy_window.item
      number = $game_party.item_number(@item)
      if @item == nil or @item.price > $game_party.gold or number == 9999
        Sound.play_buzzer
      else
        Sound.play_decision
        max = @item.price == 0 ? 9999 : $game_party.gold / @item.price
        max = [max, 9999 - number].min
        @buy_window.active = false
        @buy_window.visible = false
        @number_window.set(@item, max, @item.price)
        @number_window.active = true
        @number_window.visible = true
      end
    end
  end
end

#==============================================================================
# ** Game_Party
#------------------------------------------------------------------------------
#  This class handles the party. It includes information on amount of gold
# and items. The instance of this class is referenced by $game_party.
#==============================================================================

class Game_Party < Game_Unit
  #--------------------------------------------------------------------------
  # * Gain Items (or lose)
  #    item          : Item
  #    n            : Number
  #    include_equip : Include equipped items
  #--------------------------------------------------------------------------
  def gain_item(item, n, include_equip = false)
    number = item_number(item)
    case item
    when RPG::Item
      @items[item.id] = [[number + n, 0].max, 9999].min
    when RPG::Weapon
      @weapons[item.id] = [[number + n, 0].max, 9999].min
    when RPG::Armor
      @armors[item.id] = [[number + n, 0].max, 9999].min
    end
    n += number
    if include_equip and n < 0
      for actor in members
        while n < 0 and actor.equips.include?(item)
          actor.discard_equip(item)
          n += 1
        end
      end
    end
  end
end