集合去重 （集合元素为引用类型）--- java 8 新特性 --- 根据元素单属性、多属性实现去重

package gentle.entity;

import lombok.Data; 

/**
 *
 * @author silence
 * @date 2018/7/6 10:58
 */
@Data // 此注解可自动生成set/get、自动重写equals/hashcode 等，不用在代码中书写相关代码。

public class User {

    private String name;
    private int age;

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

  /**
     *  for循环
     * @param list
     * @param <T>
     */
    public static <T> void listFor(List<T> list) {
        list.forEach(each -> System.out.print(each+" "));
    }

  

    /**
     * 按对象属性去重
     *
     * @return
     */
    public static List<User> deleteSameByOne(List<User> users) {

        // 1.单个属性去重
        return users.stream().collect(Collectors.collectingAndThen(
                Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(User::getAge))),
                ArrayList::new));
    }

    /**
     * 按对象属性去重
     *
     * @return
     */
    public static List<User> deleteSameByMany(List<User> users) {

        // 2.多属性去重：把多个属性拼起来( 本质上还是单属性去重 )
        return users.stream().collect(Collectors.collectingAndThen(
                Collectors.toCollection(() -> new TreeSet<>(
                        Comparator.comparing(userDep -> userDep.getName() + userDep.getAge()))),
                ArrayList::new));
    }



  /**
     * 基本数据类型去重
     *
     * @param list
     * @param <T>
     * @return
     */
    public static <T> List<T> deleteSame(List<T> list) {
        return list.stream().distinct().collect(Collectors.toList());
    }

        List<User> userList = new ArrayList<User>(){{add(new User("花间",24));}
                                                     {add(new User("暮云",28));}
                                                     {add(new User("暮云",28));}
                                                     {add(new User("彻风",24));}
                                                     {add(new User("弥禁",16));}
                                                     {add(new User("清寞",24));}};


        
        System.out.println("去掉同龄的：\n"+deleteSameByOne(userList));
        System.out.println("去掉同龄且同名的：\n"+deleteSameByMany(userList));