关于debug

[myj870517]

//: initialization/TerminationCondition.java
// Using finalize() to detect an object that
// hasn't been properly cleaned up.

class Book {
boolean checkedOut = false;

Book(boolean checkOut) {
checkedOut = checkOut;
}

void checkIn() {
checkedOut = false;
}

protected void finalize() {
if (checkedOut)
System.out.println("Error: checked out");
// Normally, you'll also do this:
// super.finalize(); // Call the base-class version
}
}

public class TerminationCondition {
public static void main(String[] args) {
Book novel = new Book(true);
// Proper cleanup:
novel.checkIn();
// Drop the reference, forget to clean up:
new Book(true);
// Force garbage collection & finalization:
System.gc();
}
} /*
* Output: Error: checked out
*/// :~


问题：
运行System.gc()上一步前checkedOut的值是ture，为什么到了System.gc()就变成false了？

[greathawker]

System.gc() 结果是不定的。
不能保证前句生成的对象会被回收。

[gesanri]

System.gc()上一步前checkedOut的值是true
到了System.gc()还是true啊
调用finalize（）方法
if (checkedOut)
System.out.println("Error: checked out");
这里因为checkedOut是true才会执行输出Error: checked out啊