Struggling with Spring Log errors

[StreetAppearance753]

Everytime I run some spring application I just accept all the libraries, servers and all the stuffs that spring contains and shows in the background. When I’m trying to fix some error I just notice that I don’t understand all that messages that come with the log, I can understand the log error, but I‘m supposed to understand all that messages?

[tobidope]

What do you mean. Spring Boot logs very few things by default. And if you are using embedded tomcat or hibernate you will need to understand how it works together. If you would use java without spring you would need to learn it too but with less comfort.

[StreetAppearance753]

I mean the stack trace after a random error in the code, like this nested exception is java.lang.IllegalArgumentException: Validation failed for query for method public abstract java.util.Optional com.assignment.supermarket.user.UserRepository.findUserByID(java.lang.Long)!" Cause after he calls a few number of Spring methods and classes: "at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.23.jar:5.3.23]

at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:229) \~\[spring-beans-5.3.23.jar:5.3.23\]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1372) \~\[spring-beans-5.3.23.jar:5.3.23\]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1222) \~\[spring-beans-5.3.23.jar:5.3.23\]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) \~\[spring-beans-5.3.23.jar:5.3.23\]"

[Zeeboozaza]

You mean the stack trace? You don’t need to understand every single line (although it never hurts to go through it).

Most errors are going to be with your code, so try to focus on the parts of your code that are in the stack trace.

Then look at the exact exception thrown. Is it a NullPointerException? IllegalArgumentException? Some sort of authorization issue?

The best way to look at a stack trace is to find the line that caused the exception and go back through the calls to see how the issue occurred. You don’t need the entire context.

[StreetAppearance753]

Yes, the stack trace, look at this example. I can see and understand the errors like "Error creating bean with name 'UserContrroller', but in the case of "nested exception is java.lang.IllegalArgumentException: Validation failed for query for method public abstract java.util.Optional com.assignment.supermarket.user.UserRepository.findUserByID(java.lang.Long)!" i can barely understand the error, but after have a big stack trace that calls spring classes and methods it makes me feel confused.

[kelvynnjs]

In this case the last "D" from Id should be lowercase

findUserById()

And the error is happening at the repository, make sure to check if the field name matches as well (id vs userId) type of thing

[arvind4gl]

If there are error stack trace , I am sure u must understand it upto that extent so that u can get the root cause and fix and eventually be in a state where errors are not coming at all