Hello.

I use the Java language.

The tests pass, but when I try to send the code, writes: "For input string:"+"." Then follows Stacktrace, in which: "Java.lang.numberformatexception: for input string:"+". Next, Stacktrace ...".

My calculator returns 0.0 with a transferred line "+". I don’t understand what needs to be returned to go these tests.

I think that the exception should be returned to such a line: "+". Since this is not a mathematical expression. I think the decision is the correctness of the exclusion. But I can’t fully understand in which form to return the exception.

Who can direct to the right thought, please write?