一个笔试题目

1. class TestA {
2. TestB b;
3. TestA() {
4. b = new TestB(this);
5. }
6. }
7. class TestB {
8. TestA a;
9. TestB(TestA a) {
10. this.a = a;
11. }
12. }
13. class TestAll {
14. public static void main (String args[]) {
15. new TestAll().makeThings();
16. // ...code continues on
17. }
18. void makeThings() {
19. TestA test = new TestA();
20. }
21. } Which two statements are true after line 15, before main completes? (Choose two)c d A. Line 15 causes a stack overflow. B. An exception is thrown at runtime. C. The object referenced by a is eligible for garbage collection. D. The object referenced by b is eligible for garbage collection. E. The object referenced by a is not eligible for garbage collection. F. The object referenced by b is not eligible for garbage collection.

答案：C D
这是一个典型的孤立岛屿的例子。要记住:一个对象，它是由另一个对象引用可以有资格
垃圾收集，如果是两个对象则构成孤立的对象岛。

:D 什么是垃圾收集？ :wink: