如何在AnyLogic中修复NullPointerException

Question

我尝试修复NullPointerException已经有一段时间了，我完全被难住了。它发生在一个“抢占”块中，但我不能确定到底是什么导致了它。

我有一种感觉，这可能是因为我是一个初学者，所以我已经将代码输入到了block块中。

我正在尝试获取另一个代理，并通过“order”代理中包含从1到8的值的参数将其发送到世界的不同部分。

在抢占单元上，我有以下代码：

if (agent.missionLocation <= 1); KC30resource1.moveTo(main.AsiaRegion.randomPointInside());
{
if (agent.missionLocation <= 2); KC30resource1.moveTo(main.AfricaRegion.randomPointInside());
}
{
if (agent.missionLocation <= 3); KC30resource1.moveTo(main.MiddleeastRegion.randomPointInside());
}
{
if (agent.missionLocation <= 4); KC30resource1.moveTo(main.EuropeRegion.randomPointInside());
}
{
if (agent.missionLocation <= 5); KC30resource1.moveTo(main.NAmericaRegion.randomPointInside());
}
{
if (agent.missionLocation <= 6); KC30resource1.moveTo(main.SAmericaRegion.randomPointInside());
}
{
if (agent.missionLocation <= 7); KC30resource3.moveTo(main.AustraliaNzRegion.randomPointInside());
}
{
if (agent.missionLocation <= 8); KC30resource2.moveTo(main.PacificRegion.randomPointInside());
}

这可能是它发生的原因吗？

Exception during discrete event execution:

NullPointerException

java.lang.NullPointerException

    at com.anylogic.libraries.processmodeling.Seize.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize$16.a(Unknown Source)

    at com.anylogic.libraries.processmodeling.Seize$16.action(Unknown Source)

    at com.anylogic.libraries.processmodeling.AsynchronousExecutor_xjal.executeActionOf(Unknown Source)

    at com.anylogic.engine.EventTimeout.execute(Unknown Source)

    at com.anylogic.engine.Engine.f(Unknown Source)

    at com.anylogic.engine.Engine.gj(Unknown Source)

    at com.anylogic.engine.Engine.e(Unknown Source)

    at com.anylogic.engine.Engine$m.run(Unknown Source)

预期的结果是单元将飞到代码中指定的GISregion。每个区域的每个“MoveTo”块都连接到抢占块。

提前谢谢你。

Answer 1

我认为您使用的抢占块是错误的。您正在尝试告诉资源在抢占对象中移动，但这不是您执行此操作的方式，请参阅有关这方面的教程。

相反，您需要用您的资源设置资源池(在您的例子中似乎是KC30 )。将其设置为10个或您拥有的任何数量。

现在在Seize中，让您的订单从资源池中抢占1个KC30。如果您愿意，您可以告诉它首先移动到订单代理：

​

要使KC30代理现在移动到具有订单的区域，您可以在抢占块之后使用"MoveTo“块，并使用您的代码将订单(及其捕获的KC30)告知您的世界区域。

PS:您的if语句可以替换为switch语句，它更优雅、更可靠，请查看:-)