单选题How can you force garbage collection of an object？（）A Garbage collection cannot be forced.B Call System.gc（）.C Call System.gc（）， passing in a reference to the object to be garbage collected.D Call Runtime.gc（）.E Set all references to the object to new values（null， for example）.
单选题
How can you force garbage collection of an object？（）
A
Garbage collection cannot be forced.
B
Call System.gc（）.
C
Call System.gc（）， passing in a reference to the object to be garbage collected.
D
Call Runtime.gc（）.
E
Set all references to the object to new values（null， for example）.
参考解析
解析：
在Java中垃圾收集是不能被强迫立即执行的。调用System.gc()或Runtime.gc()静态方法不能保证垃圾收集器的立即执行，因为，也许存在着更高优先级的线程。所以选项B、D不正确。选项C的错误在于，System.gc()方法是不接受参数的。选项E中的方法可以使对象在下次垃圾收集器运行时被收集。
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