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I am new to spring Boot and spring when i try to run the following code i am getting NullPointerException. 

@SpringBootApplication public class cardApplication implements CommandLineRunner{ private JourneyService journeyService; public static void main(String[] args) { SpringApplication.run(cardApplication.class, args); } @Override public void run(String... args) throws Exception { Scanner scan = new Scanner(System.in); String name = scan.next(); Double balance = scan.nextDouble(); Card card = new Card(name, balance); // Travel begins Barrier checkIntoTube = new Barrier(card, Direction.IN, TravelMode.TUBE, Stations.Holborn); Barrier checkOutTube = new Barrier(card, Direction.OUT, TravelMode.TUBE, Stations.EarlsCourt); journeyService.startTubeJourney(checkIntoTube); journeyService.endTubeJourney(checkOutTube); }

}

And My Exception trace looks like 

2018-03-10 11:14:44.016 INFO 20240 --- [ main] ConditionEvaluationReportLoggingListener : Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled. 2018-03-10 11:14:44.039 ERROR 20240 --- [ main] o.s.boot.SpringApplication : Application run failed java.lang.IllegalStateException: Failed to execute CommandLineRunner at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:793) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE] at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:774) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:335) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1234) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE] at com.alefedu.oyestercard.travel.OystercardApplication.main(OystercardApplication.java:17) [classes/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_73] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_73] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_73] at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_73] at org.springframework.boot.maven.AbstractRunMojo$LaunchRunner.run(AbstractRunMojo.java:496) [spring-boot-maven-plugin-2.0.0.RELEASE.jar:2.0.0.RELEASE] at java.lang.Thread.run(Thread.java:745) [na:1.8.0_73] Caused by: java.lang.NullPointerException: null at com.alefedu.oyestercard.travel.OystercardApplication.run(OystercardApplication.java:34) [classes/:na] at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:790) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE] ... 11 common frames omitted 2018-03-10 11:14:44.043 INFO 20240 --- [ main] ConfigServletWebServerApplicationContext : Closing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5599596c: startup date [Sat Mar 10 11:14:27 IST 2018]; root of context hierarchy 2018-03-10 11:14:44.050 INFO 20240 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Unregistering JMX-exposed beans on shutdown [WARNING] java.lang.reflect.InvocationTargetException at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at org.springframework.boot.maven.AbstractRunMojo$LaunchRunner.run(AbstractRunMojo.java:496) at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.IllegalStateException: Failed to execute CommandLineRunner at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:793) at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:774) at org.springframework.boot.SpringApplication.run(SpringApplication.java:335) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246) at org.springframework.boot.SpringApplication.run(SpringApplication.java:1234) at com.alefedu.oyestercard.travel.OystercardApplication.main(OystercardApplication.java:17) ... 6 more Caused by: java.lang.NullPointerException at com.alefedu.oyestercard.travel.OystercardApplication.run(OystercardApplication.java:34) at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:790) ... 11 more [INFO] ------------------------------------------------------------------------ [INFO] BUILD FAILURE [INFO] ------------------------------------------------------------------------

I do not understand where i am doing wrong.

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9
  • You have not autowired service. Commented Mar 10, 2018 at 6:46
  • Still not working after autowired. Commented Mar 10, 2018 at 6:59
  • First try writing without any code inside run method Commented Mar 10, 2018 at 7:00
  • Are you sure you have pasted correct code? Because in the stacktrace, class name is OystercardApplication and in the code class name is cardApplication Commented Mar 10, 2018 at 7:02
  • Yes, I just changed the app name while writing here. @SanjayPatel it was working with code inside run method except when i call my journeyService method Commented Mar 10, 2018 at 8:04

2 Answers 2

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3

I had the same issue. I have autowired the class which I have invoked. It worked for me.

@Autowired private JourneyService journeyService;
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1

In order for something to be injected by Springs IoC container it must be defined as a bean or be an internal Spring object such as ApplicationContext.

So, define a new XML configuration file or use Java configuration to define the service as a bean and then inject it with @Autowired or @Inject.

Please refer to the Spring documentation for more details.

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