How to tell if an object is still alive?
1. Reference counting
There is a disadvantage that it cannot solve the circular dependency problem
2. Accessibility Analysis
Commonly used as the root is mainly in the global reference and execution context
Referenced objects in the virtual machine stack
The object referenced by the constant in the method area
The object referenced by the static variable in the method area
Commonly used garbage collection methods
1. Mark Clear
2. Mark finishing
3. Replication algorithm
4. Generational algorithm
The generational algorithm is mainly aimed at heap partitioning. The new generation adopts the replication algorithm, and the old generation adopts the mark sorting algorithm.