垃圾回收有关问题

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;            }}