其實我覺得可以參考JAVA原廠對各版本的支援
去思考各版本還可以用多久的問題
投資舊技術也要評估未來是否能帶來幫助
https://www.oracle.com/java/technologies/java-se-support-roadmap.html

裡面有提到SE8
End of Public Updates of Java SE 8
Java SE 8 has gone through the End of Public Updates process for legacy releases. Oracle will continue to provide free public updates and auto updates of Java SE 8 indefinitely for Personal, Development and other Users via java.com. Oracle will provide at least 18 months notice on this page and other communication channels if an end of availability date is set. Developers can find Oracle Java SE updates, including Oracle Java SE 8, 11 and current releases, free for development on OTN. As of the April 16, 2019 quarterly critical patch update, Oracle Customers should access updates to Java SE 8 for commercial use from Oracle through My Oracle Support and via auto update where applicable (Visit My.Oracle Support Note 1439822.1 - All Java SE Downloads on MOS – Requires Support Login).

Oracle does not plan to migrate desktops from Java SE 8 to later versions via the auto update feature. This includes the Java Plugin and Java Web Start. Instead of relying on a browser-accessible system JRE, we encourage application developers to use the packaging options introduced with Java SE 9 to repackage and deliver their Java applications as stand-alone applications that include their own custom runtimes.

當初我自學springboot是看Sping官網的getting start
希望對你有幫助！

發現有很多Java寫法是自己不知道的

這好辦
就 SE8 SE9 的書各找一本來
裡面有提到你不知道的部份比較多的
就選那一本就好了

或者不做選擇
兩本都買更好