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Troubleshooting Common Java Exceptions

Troubleshooting Common Java Exceptions

  • Below is an example of NullPointer Exception
     Exception in thread "main" java.lang.NullPointerException
  at com.example.myproject.Object1.getValue(Object1.java:16)
  at com.example.myproject.Object2.getNumericValue(Object2.java:25)
  at com.example.myproject.Object3.main(Object3.java:14)
    • In this case we need to navigate to the file Object1 and review the method called getValue() to determine what happened
    • The remaining lines give the further information about how the exception was arrived at.
  • Most of the times we'll have something different to the above, but the above given can be taken as a basic example of how to find out the issue.
  • Let us look at the below log once
     Exception in thread "main" java.lang.NullPointerException
  at com.example.myproject.Object1.getValue(Object1.java:16)
  at com.example.myproject.Object2.getNumericValue(Object2.java:25)
  at com.example.myproject.Object3.main(Object3.java:14)
 Caused by: java.lang.IllegalReferenceException
  at com.example.myproject.Object1.getParentValue(Object1.java:22)
    • This means that we have a NullPointer exception in Object1 at the getValue() method occured as Object1 and getParentValue() method thrown a IllegalReferenceException and this is the initial cause of the problem.
    • If we have multiple Caused by sections then the lowest is the initial cause of the problem.

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