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Figure 8-5.

Generation 0 objects that survive a garbage collection are promoted to generation 1.

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If all generation 0 objects have been evaluated, but additional memory is still required, genera-

tion 1 objects are then investigated for their “reachability” and collected accordingly. Surviving

generation 1 objects are then promoted to generation 2. If the garbage collector 

still requires addi-

tional memory, generation 2 objects are then evaluated for their reachability. At this point, if a

generation 2 object survives a garbage collection, it remains a generation 2 object given the prede-

fined upper limit of object generations.

The bottom line is that by assigning a generational value to objects on the heap, newer objects

(such as local variables) will be removed quickly, while older objects (such as a program’s applica-

tion object) are not “bothered” as often.