import java.util.Comparator;
  
 public class GoodsSorts implements Comparator {
     public int compare(Object o1,Object o2){
         Goods g1=(Goods)o1;
         Goods g2=(Goods)o2;
         System.out.println("调用排序方法");
         if(g1.getPrice()>g2.getPrice()){
             return -1;
         }else if(g1.getPrice()<g2.getPrice()){
             return 1;
         }
         return 0;
     }
 }
 测试类import java.util.TreeSet;
  
 public class test63 {
     public static void main(String[] args){
         TreeSet tree=new TreeSet(new GoodsSorts());//创建一个采用默认树形自然排序的对象
         Goods g0=new Goods();
         g0.setName("剃须刀");
         g0.setPrice(2000.0);
         Goods g1=new Goods();
         g1.setName("西瓜");
         g1.setPrice(7000.0);
         Goods g2=new Goods();
         g2.setName("小刀");
         g2.setPrice(3000.0);
         Goods g3=new Goods();
         g3.setName("矿泉水");
         g3.setPrice(4000.0);
         tree.add(g3);
         tree.add(g2);
         tree.add(g1);
         tree.add(g0);
         for(Object o:tree){
             System.out.println(((Goods)o).getName()+"\t"+((Goods)o).getPrice());
         }
         System.out.println("第一个"+((Goods)tree.first()).getName());
         System.out.println("最后一个"+((Goods)tree.last()).getName());
     }
 }

运行结果

java123-treeset排序集合_排序方法