什么时候回收垃圾
public   class   RJMould{

           
    StringBuffer   sb;

      public   static   void   main(String[]   args)

        {

                      RJMould   rjm   =   new   RJMould();

                        rjm.kansas();

    }
            public   void   kansas(){

                        sb   =   new   StringBuffer( "Manchester ");//8
                        StringBuffer   sb2   =sb;//9

                        String   Buffer   sb3   =   new   StringBuffer( "OK ");//10

                          sb   =   sb3;//11
                            sb3   =   null;//12

                          sb2   =   null;   //13


      }
   
}

    垃圾回收机制上说当代码无法在被访问的时候，就开始回收，那么在12行的时候就开始了，但是在SCJP考试卷子上它确说是13行，希望高人指点。

------解决方案--------------------
例子：
class Test{
String name;
Long id;

public EqualObject(String name, Long id) {
super();
this.name = name;
this.id = id;
}

protected void finalize() throws Throwable {
System.out.println( "finalize( " + name + ", " + id + ") ");
}
}
public class MyTest{
public static void main(String[] args) {
EqualObject a = new Test( "1 ", new Long(1));
a = new Test( "2 ", new Long(2));
a = new Test( "3 ", new Long(3));
a = new Test( "4 ", new Long(4));
System.gc(); //如果没有这句，没有打印

a= null;
a = new Test( "5 ", new Long(5));
a= null;
a = new Test( "6 ", new Long(6));
a= null;
a = new Test( "7 ", new Long(7));
a= null;
System.gc(); //同上
}
}
------解决方案--------------------
1.gc很懒
2.gc线程优先级低