Class loading method and process, the principle and use of reflection, why springbean uses reflection instead of new, when is the static code block loaded, when is the class allocated on the stack, query of the first three window functions in the group, and what is stored in the method area in the JVM , advanced scheduling, when to use short jobs first, how to ensure security in the https certificate authentication process, how to implement zero copy in java, why volatile cannot guarantee atomicity if it is not in the working memory, how to ensure persistence in redolog, virtual memory, b+ tree, Output the longest common subsequence of a string