public void case14() {
    ArrayList<User> users = new ArrayList<User>();
    users.add(new User(1, "Adimas Lutfi Wicaksono"));
    users.add(new User(2, "Salman Alfarisi"));
    users.add(new User(3, "Muhammad Sholeh"));

    ArrayList<User> usersNew = new ArrayList<User>();
    usersNew.add(new User(4, "Yadi Cahyadi"));
    usersNew.add(new User(5, "Maya Maulani"));

    users.addAll(usersNew);
}

private class User {
    private Integer id;
    private String name;
    private Integer gender = 1;

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

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

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getGender() {
        return gender == 1 ? "Male" : "Female";
    }

    public String toString() {
        return "ID: " + getId() + " Name: " + getName() + " Gender: " + getGender() + "\n";
    }
}