Groovy different results on using equals() and == on a GStringImpl

by

Nice question, the surprising thing about the code above is that

println "${'test'}".equals('test')

returns false. The other line of code returns the expected result, so let’s forget about that.

Summary

"${'test'}".equals('test')

The object that equals is called on is of type GStringImpl whereas 'test' is of type String, so they are not considered equal.

But Why?

Obviously the GStringImpl implementation of equals could have been written such that when it is passed a String that contain the same characters as this, it returns true. Prima facie, this seems like a reasonable thing to do.

I’m guessing that the reason it wasn’t written this way is because it would violate the equals contract, which states that:

It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.

The implementation of String.equals(Object other) will always return false when passed a GSStringImpl, so if GStringImpl.equals(Object other) returns true when passed any String, it would be in violation of the symmetric requirement.

More Related Contents:

  1. Split a string in groovy
  2. How do I get the output of a shell command executed using into a variable from Jenkinsfile (groovy)?
  3. Groovy executing shell commands
  4. Understanding the groovy syntax in a gradle task definition
  5. Including a groovy script in another groovy
  6. Creating a Jenkins environment variable using Groovy
  7. Can you break from a Groovy “each” closure?
  8. How do I create and access the global variables in Groovy?
  9. What the difference in applying gradle plugin
  10. Load script from groovy script
  11. Get values from properties file using Groovy
  12. Groovy: what’s the purpose of “def” in “def x = 0”?
  13. Converting a string to int in Groovy
  14. How can I use the Jenkins Copy Artifacts Plugin from within the pipelines (jenkinsfile)?
  15. groovy execute with parameters containing spaces
  16. Reading file from Workspace in Jenkins with Groovy script
  17. Recommended way to stop a Gradle build
  18. Difference between Groovy Binary and Source release?
  19. Overloading operator== versus Equals()
  20. How to retrieve Jenkins build parameters using the Groovy API?
  21. Overriding the java equals() method – not working?
  22. Why doesn’t Java offer operator overloading?
  23. Why would you use String.Equals over ==? [duplicate]
  24. why equals() method when we have == operator? [duplicate]
  25. Operator overloading outside class [duplicate]
  26. Overloading assignment operator in C++
  27. How do I auto load a database jar in Groovy without using the -cp switch?
  28. list of ruby operators that can be overridden/implemented
  29. Is it possible in java make something like Comparator but for implementing custom equals() and hashCode()
  30. How could comma separated initialization such as in Eigen be possibly implemented in C++?

Leave a Comment