关于java垃圾回收

原创于 2010-12-28 14:06:00 发布 · 377 阅读

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#java #object #float #null #class #c

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本文通过一个Java示例探讨了对象何时符合垃圾回收条件的问题。在示例中，一个浮点数对象被创建并赋值给一个对象引用，随后该引用被设置为null，但对象仍可通过数组引用访问。文章解释了为什么此对象不会立即成为垃圾收集的目标。

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Given:
public class X {
public object m() {
object o = new float (3.14F); //line 3
object [] oa = new object [1];
oa[0]= o; //line 5
o = null; //line 6
oa[0] = null; //line 7
return o; //line 8
}
}
When is the float object created in line 3, eligible for
garbage collection?
A. Just after line 5
B. Just after line 6
C. Just after line 7
D. Just after line 8(that is, as the method returns)
答案C

Given:
1. public class X (
2. public object m () {
3. object o = new float (3.14F);
4. object [] oa = new object [1];
5. oa[0]= o;
6. o = null;
7. return oa[0];
8. }
9. )
When is the float object created in line 3, eligible for garbage collection?
A. Just after line 5
B. Just after line 6
C. Just after line 7 (that is, as the method returns)
D. Never in this method.
答案: D