It also can be done without using reflection.

The solution is dynamic. When your class is extended with new fields, you don't need to add them to a list or add another null check.

Note:

I used the EqualsAndHashCode annotation by Lombok.

You have to make sure the default constructor is not implemented with custom behavior and your fields does not have a default value other than the built-in java default (null for reference types, 0 for int, etc.).

@EqualsAndHashCode
public class User
{
    private static User EMPTY = new User();

    private String id = null;
    private String name = null;

    private User()
    {
    }

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

    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }

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

    public boolean isEmpty()
    {
        return this.equals(EMPTY);
    }
}

This can be done fairly easily using a Lombok generated equals and a static EMPTY object:

import lombok.Data;

public class EmptyCheck {
    public static void main(String[] args) {
        User user1 = new User();

        User user2 = new User();
        user2.setName("name");

        System.out.println(user1.isEmpty()); // prints true
        System.out.println(user2.isEmpty()); // prints false
    }

    @Data
    public static class User {
        private static final User EMPTY = new User();

        private String id;
        private String name;
        private int age;

        public boolean isEmpty() {
            return this.equals(EMPTY);
        }
    }
}

Prerequisites:

• Default constructor should not be implemented with custom behavior as that is used to create the EMPTY object
• All fields of the class should have an implemented equals (built-in Java types are usually not a problem, in case of custom types you can use Lombok)

Advantages:

• No reflection involved
• As new fields added to the class, this does not require any maintenance as due to Lombok they will be automatically checked in the equals implementation
• Unlike some other answers this works not just for null checks but also for primitive types which have a non-null default value (e.g. if field is int it checks for 0, in case of boolean for false, etc.)

It also can be done without using reflection.

The solution is dynamic. When your class is extended with new fields, you don't need to add them to a list or add another null check.

Note:

I used the EqualsAndHashCode annotation by Lombok.

You have to make sure the default constructor is not implemented with custom behavior.

@EqualsAndHashCode
public class User
{
    private static User EMPTY = new User();

    private String id = null;
    private String name = null;

    private User()
    {
    }

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

    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }

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

    public boolean isEmpty()
    {
        return this.equals(EMPTY);
    }
}

It also can be done without using reflection.

The solution is dynamic. When your class is extended with new fields, you don't need to add them to a list or add another null check.

Note:

I used the EqualsAndHashCode annotation by Lombok.

You have to make sure the default constructor is not implemented with custom behavior and your fields does not have a default value other than the built-in java default (null for reference types, 0 for int, etc.).

@EqualsAndHashCode
public class User
{
    private static User EMPTY = new User();

    private String id = null;
    private String name = null;

    private User()
    {
    }

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

    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }

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

    public boolean isEmpty()
    {
        return this.equals(EMPTY);
    }
}