垃圾回收问题
有如下问题，请大家解释一下，谢谢：
interface Animal{ void makeNoise();}class Horse implements Animal{ Long weight=1200L; public void makeNoise(){ System.out.println("vinny"); }}public class lcelandic extends Horse{ /** * @param args the command line arguments */ public static void main(String[] args) { // TODO code application logic here lcelandic i1=new lcelandic(); lcelandic i2=new lcelandic(); lcelandic i3=new lcelandic(); i3=i1;i1=i2;i2=null;i3=i1; }}