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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