Interview summary of large factory Daquan II

1、java virtual machine jvm Class loading mechanism of

The whole process of class loading ：
load --> link （ verification -> Get ready -> analysis ）–> initialization

Loading phase ：
1. Load the binary byte stream of the class into the method area through the fully qualified class name of the class （ Class variables ）.

Link phase ：
1.（ verification ） Verify whether the information contained in the virtual machine byte stream meets the requirements of the current virtual machine .
2.（ Get ready ） Set the default initial value for class variables ,final Decorated memory will be allocated during compilation , Explicit initialization in the preparation phase , And instance variables are assigned to java In the pile .
3.（ analysis ） The process of converting a symbolic reference in a constant pool to a direct reference ; Analysis is in jvm Execute initialization before executing .

Initialization phase ：
1. The process of performing class constructor methods ,jvm Execute subclass constructor , Make sure that the parent constructor has been executed ,jvm Ensure that the constructor of a class is locked synchronously in the case of multithreading ; After the execution, the loading of the class is completed .