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Java

Roger Panella
Roger Panella
5,968 Points

Java repl "no unique maximal instance" error

I've installed the Java repl on my machine using Homebrew. I keep getting an error that I don't know how to fix, and am not sure what's producing it. It happens a lot, but here's one way I'm able to produce it:

First, I enter this example from the "Incrementing and Decrementing" video:

java> int example = 1 repl displays: int example = 1

Then, I enter:

java> int example = example + 1

At this point, I get the error:

ERROR: /var/folders/1b/c7kfxf2s4297q8rqqm4x_wsw0000gn/T/JavaREPL/fceec614-9263-4ec1-ac7b-5b7df62de85b/Evaluation.java:7: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds int,java.lang.Object public int example = valueOf("example"); ^

Also, once the commands above have produced the error, it seems like everything I enter produces the same error.

For example, if I enter:

java> int example2 = 2

I get this:

ERROR: /var/folders/1b/c7kfxf2s4297q8rqqm4x_wsw0000gn/T/JavaREPL/fceec614-9263-4ec1-ac7b-5b7df62de85b/Evaluation.java:7: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds int,java.lang.Object public int example = valueOf("example"); ^

Any ideas? I saw changing the JDK version and also changing the bits as solutions on StackOverflow, but wasn't sure how to do that or if that's what I need to do.

1 Answer

Craig Dennis
STAFF
Craig Dennis
Treehouse Teacher

My guess is you can't define the variable and increment it in the same go.

int example = 1;
example = example + 1;

Is what you are looking for I think ;)

Looks like you found a juicy bug in the REPL tool!