JAVA中List對(duì)象去除重復(fù)值，大致分為兩種情況，一種是List<String>、List<Integer>這類，直接根據(jù)List中的值進(jìn)行去重

List<String> listStr = Arrays.asList("a", "b", "c", "a","a");
List<String> filltrList = listStr.stream().distinct().collect(Collectors.toList());

另一種是List<User>這種，List中存的是javabean對(duì)象，需要根據(jù)List中對(duì)象的某個(gè)值或某幾個(gè)值進(jìn)行比較去重。需要重寫對(duì)象的equals和hashCode

public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    private Integer id;

    private String username;

    private String sex;

    private LocalDate birthday;

    private String address;

    private String password;

    private Integer orgId;

    @Override
    public boolean equals(Object obj) {
        if(this == obj){
            return true;//地址相等
        }
        if(obj == null){
            return false;//非空性：對(duì)于任意非空引用x，x.equals(null)應(yīng)該返回false。
        }

        if(obj instanceof User){
            User user = (User) obj;
            //需要比較的字段相等，則這兩個(gè)對(duì)象相等
            if(this.username.equals(user.getUsername())){
                return true;
            }
        }
        return false;
    }

    @Override
    public int hashCode() {
        int result = 17;
        result = 31 * result + (username == null ? 0 : username.hashCode());
        return result;
    }
}

List<User> list = new ArrayList<>();
User u1 = new  User();
u1.setId(1);
u1.setUsername("張三");
list.add(u1);

User u2 = new  User();
u2.setId(1);
u2.setUsername("張三");
list.add(u2);

User u3 = new  User();
u3.setId(1);
u3.setUsername("張三");
list.add(u3);

List<User> collect = list.stream().distinct().collect(Collectors.toList());