上课编写的一个简单的电梯模拟，可容纳六人，左边控制按钮控制乘客上电梯，右边控制按钮控制乘客下电梯，顶部显示电梯当前运行状态。-class prepared a simple elevator simulation, which can accommodate six people, left control button to control passengers on the elevator, the right control button to control passengers under the lift, lift the top of the current operating state.