See how much volatile you know

For the sake of running speed ,java The compiler will put frequently accessed variables into the cache （ Strictly speaking, it should be working memory ） in , Read variables are read from the cache . But in multithreaded programming , There may be inconsistencies between the values in memory and the values in the cache .volatile Used to limit that variables can only be read from memory , Ensure that for all threads , The values are consistent . however volatile Atomicity is not guaranteed , You can't guarantee thread safety