java Comparator 用法 例子

package test; import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Test { public List<User> initUser(){ List<User> userlist = new ArrayList<User>(); for(int i = 0;i<10;i++){ User u = new User(); u.setId(i); u.setUsername("a"+i); userlist.add(u); } return userlist; } public List<UserInfo> initInfo(List<User> ul){ List<UserInfo> userInfo = new ArrayList<UserInfo>(); int i = 0; for(User u : ul){ UserInfo ui = new UserInfo(); ui.setId(i); ui.setUId(u.getId()); ui.setOrder((int) (Math.floor(Math.random()*10))); i++; userInfo.add(ui); } return userInfo; } @SuppressWarnings("unchecked") public static void main(String as[]){ Test t = new Test(); List<User> ul =t.initUser(); List<UserInfo> ui = t.initInfo(t.initUser()); for(User u : ul){ System.out.println(u.getUsername()+"before---"); } // MyComparator comp = new MyComparator(); // comp.setUi(ui); // Collections.sort(ul,comp); for(User u : ul){ System.out.println(u.getUsername()); } } }