1.實現Comparable接口(如果List<Object>中Object實現了Comparator接口，便可以直接用以下Collections.sort的方式對List進行排序)

public class Test {

?public static void main(String[] args) {
??List<User> userList = new ArrayList<User>();
??userList.add(new User(3, "3"));
??userList.add(new User(2, "2"));
??userList.add(new User(5, "5"));
??userList.add(new User(7, "7"));
??Collections.sort(userList);
??for (User user : userList) {
???System.out.println(user.getAge());
??}
?}
}

class User implements Comparable<User> {
?private int age;
?private String name;

?public User(int age, String name) {
??super();
??this.age = age;
??this.name = name;
?}

?public int getAge() {
??return age;
?}

?public void setAge(int age) {
??this.age = age;
?}

?public String getName() {
??return name;
?}

?public void setName(String name) {
??this.name = name;
?}

?@Override
?public int compareTo(User user) {

??return age - user.getAge();
?}
}

2.實現Comparator接口

public class Test {

?public static void main(String[] args) {
??List<User> userList = new ArrayList<User>();
??userList.add(new User(3, "3"));
??userList.add(new User(2, "2"));
??userList.add(new User(5, "5"));
??userList.add(new User(7, "7"));
??Collections.sort(userList,new CompareUser());
??for (User user : userList) {
???System.out.println(user.getAge());
??}
?}
}

class CompareUser implements Comparator<Object>{

?@Override
?public int compare(Object arg0, Object arg1) {
??User user1=(User)arg0;
??User user2=(User)arg1;
??return user1.getName().toLowerCase().compareTo(user2.getName().toLowerCase());
?}
?
}

class User?? {
?private int age;
?private String name;

?public User(int age, String name) {
??super();
??this.age = age;
??this.name = name;
?}

?public int getAge() {
??return age;
?}

?public void setAge(int age) {
??this.age = age;
?}

?public String getName() {
??return name;
?}

?public void setName(String name) {
??this.name = name;
?}

}

轉載于:https://blog.51cto.com/5618698/1627229

《新程序員》：云原生和全面數字化實踐50位技術專家共同創作，文字、視頻、音頻交互閱讀

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