Java 方法上的NullPointerException（NativeMethodAccessorImpl.invoke0（本机方法）

我正在创建一个计划的方法来创建上个月的发票（为了测试目的，当前设置为每5秒一次）。我在试图从我的shiftServiceService获取shiftServices的行上得到一个NullPointerException

@Scheduled(cron = "*/5 * * * * *")
    public void createLastMonthInvoices() {
        List<Client> clients = clientService.getClientList();
        System.out.println("Clients size: " + clients.size());
        for (Client client : clients) {
            System.out.println("Client ID: " + client.getId());
            List<ShiftService> shiftServices = shiftServiceService.getLastMonthShiftServicesByClient(client.getId());
            if (!ObjectUtils.isEmpty(shiftServices)) {
                System.out.println("Services size: " + shiftServices.size());
        }
    }
}

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您正在打印一个空变量

System.out.println("Client ID: " + client.getId());

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有一件事你可以检查。一件是shiftServiceService对象是否初始化。

看起来对象shiftServiceService没有初始化，仍然为空。你需要显示

InvoiceService

如何声明

shiftServiceService

属性。@RahulAgrawal哦，我的天啊，你说得对……麻烦你了。哑巴error.check InvoiceService.java行号40正如我所说，clientId打印正确，例如：Client ID:35

java.lang.NullPointerException: null
    at com.bitweb.syda.service.invoice.InvoiceService.createLastMonthInvoices(InvoiceService.java:40)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84)
    at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
    at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93)
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)

System.out.println("Client ID: " + client.getId());