这里新建一个UserInfo对象，用来测试lambda表达式排序，属性如下：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;
}测试
public void setName(String name) {
this.name = name;
}
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开始造数据，测试下按照年龄大小正序排序：public static void main(String[] args) {
UserInfo user1 = new UserInfo(1, 20, "赵");
UserInfo user2 = new UserInfo(2, 25, "钱");
UserInfo user3 = new UserInfo(3, 23, "孙");
UserInfo user4 = new UserInfo(7, 16, "李");
UserInfo user5 = new UserInfo(6, 19, "周");
UserInfo user6 = new UserInfo(5, 12, "吴");
List userInfoList = new ArrayList<>();
userInfoList.add(user2);
userInfoList.add(user1);
userInfoList.add(user3);
userInfoList.add(user4);
userInfoList.add(user5);
userInfoList.add(user6);
//使用lambda表达式对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());
}
}
输出结果如下：
测试按照年龄大小倒序排序：public static void main(String[] args) {
UserInfo user1 = new UserInfo(1, 20, "赵");
UserInfo user2 = new UserInfo(2, 25, "钱");
UserInfo user3 = new UserInfo(3, 23, "孙");
UserInfo user4 = new UserInfo(7, 16, "李");
UserInfo user5 = new UserInfo(6, 19, "周");
UserInfo user6 = new UserInfo(5, 12, "吴");
List userInfoList = new ArrayList<>();
userInfoList.add(user2);
userInfoList.add(user1);
userInfoList.add(user3);
userInfoList.add(user4);
userInfoList.add(user5);
userInfoList.add(user6);
//使用lambda表达式对age大小倒序排序,发现就是多加了个reversed()方法
userInfoList = userInfoList.stream().sorted(Comparator.comparing(UserInfo::getAge).
reversed()).collect(Collectors.toList());
for (UserInfo userInfo : userInfoList) {
System.out.println(userInfo.toString());
}
}
输出结果如下：
总结下排序使用方法：
1、按照某个字段正序排序：userInfoList.stream().sorted(Comparator.comparing(UserInfo::getAge)).collect(Collectors.toList());
2、按照某个字段倒序排序：userInfoList.stream().sorted(Comparator.comparing(UserInfo::getAge).reversed()).collect(Collectors.toList());
以上各种参数根据自己业务对号入座即可。
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