Re: RFR: 8266972: Use String.concat() in j.l.Class where invokedynamic-based String concatenation is not available

[Сергей Цыпанов]

> Before we start to change every usage of String+String into String.concat, 
> shouldn't the compiler be so smart to do that for us?
> Currently it compiles to invokedynamic if available and to using 
> StringBuilder otherwise. Now why doesn't it compile to String.concat instead 
> of StringBuilder for the case when invokedynamic is not available as target?

I think the main reason is that

String str = "smth is " + null;

returns "smth is null" and with current implementation of String.concat()
the same expression throws NPE. See the code of String.concat():

public String concat(String str) {
    if (str.isEmpty()) {
        return this;
    }
    return StringConcatHelper.simpleConcat(this, str);
}

Regards,
Sergey