這里新建一個UserInfo對象,用來測試lambda表達式排序,屬性如下:
public class UserInfo { private int id; private int age; private String name; public UserInfo(int id, int age, String name) { this.id = id; this.age = age; this.name = name; } public int getId() { return id; } public void setId(int id) { this.id = id; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; }測試 public void setName(String name) { this.name = name; }
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開始造數(shù)據(jù),測試下按照年齡大小正序排序:
public static void main(String[] args) { UserInfo user1 = new UserInfo(1, 20, "趙"); UserInfo user2 = new UserInfo(2, 25, "錢"); UserInfo user3 = new UserInfo(3, 23, "孫"); UserInfo user4 = new UserInfo(7, 16, "李"); UserInfo user5 = new UserInfo(6, 19, "周"); UserInfo user6 = new UserInfo(5, 12, "吳"); List<UserInfo> userInfoList = new ArrayList<>(); userInfoList.add(user2); userInfoList.add(user1); userInfoList.add(user3); userInfoList.add(user4); userInfoList.add(user5); userInfoList.add(user6); //使用lambda表達式對age大小正序排序 userInfoList = userInfoList.stream().sorted(Comparator.comparing(UserInfo::getAge)) .collect(Collectors.toList()); for (UserInfo userInfo : userInfoList) { System.out.println(userInfo.toString()); } }
輸出結(jié)果如下:
測試按照年齡大小倒序排序:
public static void main(String[] args) { UserInfo user1 = new UserInfo(1, 20, "趙"); UserInfo user2 = new UserInfo(2, 25, "錢"); UserInfo user3 = new UserInfo(3, 23, "孫"); UserInfo user4 = new UserInfo(7, 16, "李"); UserInfo user5 = new UserInfo(6, 19, "周"); UserInfo user6 = new UserInfo(5, 12, "吳"); List<UserInfo> userInfoList = new ArrayList<>(); userInfoList.add(user2); userInfoList.add(user1); userInfoList.add(user3); userInfoList.add(user4); userInfoList.add(user5); userInfoList.add(user6); //使用lambda表達式對age大小倒序排序,發(fā)現(xiàn)就是多加了個reversed()方法 userInfoList = userInfoList.stream().sorted(Comparator.comparing(UserInfo::getAge). reversed()).collect(Collectors.toList()); for (UserInfo userInfo : userInfoList) { System.out.println(userInfo.toString()); } }
輸出結(jié)果如下:
總結(jié)下排序使用方法:
1、按照某個字段正序排序:
userInfoList.stream().sorted(Comparator.comparing(UserInfo::getAge)).collect(Collectors.toList());
2、按照某個字段倒序排序:
userInfoList.stream().sorted(Comparator.comparing(UserInfo::getAge).reversed()).collect(Collectors.toList());
以上各種參數(shù)根據(jù)自己業(yè)務(wù)對號入座即可。
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