The difference between the new generation and the old age ( Ali interviewer title ):
The so-called new generation and the old year is directed to the generational collection algorithm defined, the new generation is divided into two zones Eden and Survivor. Plus years old on the three areas. Data will be assigned to the Eden area which (of course there are special circumstances, if a large object that will be put directly to the old year (large objects are requires a lot of java object contiguous memory space).) When Eden there is not enough space for time jvm triggered initiate a Minor GC. If the object is still alive after one Minor GC, and can be accepted Survivor space, it will be moved to Survivor space them. And the age is set to 1, the object survived every once in Survivor Minor GC, the age is increased by one, when the age reaches a certain level (the default is 15), they will be promoted to the old era, of course, promoted years old the age can be set. If old's full implementation: Full GC because they do not often performed, so the use of the Mark-Compact algorithm cleanup