java学习（123）：treeset排序集合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