class Chair
{
public static long created = 0;
public static long finalized = 0;
public static boolean gcrun = false;
public static boolean f = false;
public long i = 0;
Chair(){
i = ++created;
if (i == 1)
{
System.out.println( "Creating start! ");
}
//System.out.print( ". ");
}
public void finalize(){
finalized++;
//System.out.print( "- ");
if (!gcrun)
{
gcrun = true;
System.out.println( "Finalized start! ");
}
if (i == 47)
{
f = true;
System.out.println( "finalized 47 chair, "+created+ " created,stop create! ");
}
if (finalized > = created)
{
System.out.println( "All chair is finalized! ");
}
}
}
public class Gc
{
public static void main(String args[]){
while(Chair.f == false){
new Chair();
new String( "take a few space ");
}
System.out.println(Chair.created+ " chair created, "+Chair.finalized+ " chair finalized! ");
System.out.println( "Bye ");
}
}
1.看了think in java中关于gc和finalize的介绍,根据书上的例子写了这个程序,但是发现All chair is finalized一直在打印出来,就是说一直在调用finalize,这让我很不解,哪位帮我看看,是什么原因
2.我如果把注解的部分打开,有可以得到正常结果,非常奇怪.
JDK是1.4.2
先谢谢大家了.
------解决方案--------------------
System.out.print();是拖延时间用的.
print()方法相对比较耗时间.
不过在我机器上,如果把两个print方法都注释掉的话,程序有一定几率会出正确结果,其他情况会导致程序一直运行下去,没出现像你说的那样All chair is finalized.
------解决方案--------------------
up
finalize是不定期调用的。
------解决方案--------------------
那你有看到书上类似于这样的一句话吧？“你永远不会知道JVM会在什么时候启动GC”
------解决方案--------------------
可能还有其它的对象(在你的程序没有看到的)也在被回收呢
------解决方案--------------------
< <Effective Java> > 中提到过，不要信赖finalize，因为即使你为你的类编写了这个方法，对消销毁的时候不一定会调用它。所以很多依赖它来释放资源的程序，往往会造成内存溢出。
------解决方案--------------------
第二章的第六项：Finalizers are unpredictable, often dangerous, and generally unnecessary.
Effective Java: Programming Language Guide =>
Chapter 2 =>
Item 6: Avoid finalizers
Finalizers are unpredictable, often dangerous, and generally unnecessary. Their use can cause erratic behavior, poor performance, and portability problems. Finalizers have a few valid uses, which we 'll cover later in this item, but as a rule of thumb, finalizers should be avoided.