Example with a context (an excerpt from "The Art & Science of Java: An Introduction to Computer Science" by Eric Roberts):
For example, executing the line
println("Top student " + topStudent)
would produce the following output:
Top student = John Doe (#20456)
Had you left out the implementation of the toString method, Java would instead use the default definition of the toString method from the Object class. The result in that case would be something like this
Top student = John Doe@154865
which is rather less informative.
I don't really understand what actually made the author choose to use Java would instead use over Java would have instead used in that sentence. To me personally, would have instead used sounds like a better choice because it makes total sense that if you had done something in the past, something different would have happened, but since you didn't do that, it didn't happen either. What gives?