AnyLogic调用setPreferredSpeed()报this.b为空的问题求助

问题描述 #

我在AnyLogic模型中尝试用以下代码修改车辆智能体种群的偏好速度：

setPreferredSpeed(10, KPH);

我将这段代码分别放在了三个位置：

• Vehicle智能体内部创建的语句图中
• Vehicle智能体属性面板的「On startup」字段
• Main模块内carMoveTo块的「On enter」字段

但无论放在哪个位置，都会抛出相同的空指针错误：

Cannot invoke "com.anylogic.libraries.road.Car_xjal.setPreferredSpeed(double, com.anylogic.engine.SpeedUnits)" because "this.b" is null

代码补全功能显示可以正常输入该函数，但运行时必定触发错误。例如将代码放在carMoveTo块的「On enter」字段时，完整错误栈如下：

Exception during discrete event execution:
Cannot invoke "com.anylogic.libraries.road.Car_xjal.setPreferredSpeed(double)" because "this.b" is null

java.lang.NullPointerException: Cannot invoke "com.anylogic.libraries.road.Car_xjal.setPreferredSpeed(double)" because "this.b" is null

at com.anylogic.libraries.road.CarExtension.setPreferredSpeed(Unknown Source)
at skagway_broadway_test.Main.setPreferredSpeed(Main.java:2116)
at skagway_broadway_test.Main._carMoveTo_onEnter_xjal(Main.java:952)
at skagway_broadway_test.Main$7.onEnter(Main.java:652)
at skagway_broadway_test.Main$7.onEnter(Main.java:1)
at com.anylogic.libraries.road.CarMoveTo.a(Unknown Source)
at com.anylogic.libraries.road.CarMoveTo$8.onEnter(Unknown Source)
at com.anylogic.libraries.processmodeling.Delay.b(Unknown Source)
at com.anylogic.libraries.processmodeling.Delay$9.onEnter(Unknown Source)
at com.anylogic.libraries.processmodeling.InputBlock$1.b(Unknown Source)
at com.anylogic.libraries.processmodeling.InPort.a(Unknown Source)
at com.anylogic.libraries.processmodeling.InPort.receiveImmediately(Unknown Source)
at com.anylogic.libraries.processmodeling.InputBlock$1.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutPort.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutPort.b(Unknown Source)
at com.anylogic.libraries.processmodeling.OutputBlock.forwardReadyEntityNotification(Unknown Source)
at com.anylogic.libraries.processmodeling.InputBlock$1.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutPort.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutPort.b(Unknown Source)
at com.anylogic.libraries.processmodeling.PlainTransfer$1.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutPort.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutPort.b(Unknown Source)
at com.anylogic.libraries.processmodeling.OutPort.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutputBlock.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutputBlock$2.a(Unknown Source)
at com.anylogic.libraries.processmodeling.OutputBlock$2.action(Unknown Source)
at com.anylogic.libraries.processmodeling.AsynchronousExecutor_xjal$a.execute(Unknown Source)
at com.anylogic.engine.LibraryEventHandler$e.execute(Unknown Source)
at com.anylogic.engine.Engine.a(Unknown Source)
at com.anylogic.engine.Engine.hk(Unknown Source)
at com.anylogic.engine.Engine$e.run(Unknown Source)

已尝试的排查步骤 #

• 参考过同类问题的解决方案，已确认Vehicle智能体的「Use in Flowcharts as Car」选项处于勾选状态，但问题未解决
• 错误触发时机：当Vehicle进入名为「straight」的carMoveTo块时，该块的「On enter」字段中调用了setPreferredSpeed(60);
• carSource块已配置偏好速度，车辆可正常在道路网络生成并进入流程

补充信息 #

相关设置截图：

• 错误场景的模块序列
• 触发错误的carMoveTo块属性
• 生成车辆的carSource块配置

希望有人能解释「this.b is null」的具体含义，并提供解决该问题的建议，我可以补充更多模型细节。

内容的提问来源于stack exchange，提问作者Ben