问二：你了解JAVA的内存模型（JMM）吗？

原理图：

注：java8中，已经将常量池移动到堆中

部件详解：

举例：执行add(1,2)

Method area is created on virtual machine startup, shared among all Java virtual machine threads and it is logically part of heap area. It stores per-class structures such as the run-time constant pool, field and method data, and the code for methods and constructors.