Short answer: Yes. That’s the point. Your ancient byte code, even from Java 1, will run under Java 11.
More detailed answer: There have been a few classes that have now finally actually been deleted from the standard library. But chances are that you did not use them.
Edit: I seem to have misread your question. No, you cannot run code compiled with Java 11 under Java 8. The bytecode version has been increased, and Java 8 will refuse to run it.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…