Builder Example

public class User implements Serializable {

	private static final long serialVersionUID = 2L;
	private Long userId;
	private String username;
	private String password;
	private String firstName;
	private String lastName;
	private String email;

	/**
	 * Gets a builder which is used to create User objects.
	 * 
	 * @return A new Builder instance.
	 */
	public static Builder getBuilder() {
		return new Builder();
	}

	/**
	 * Gets a builder which is used to create User objects.
	 * 
	 * @param preBuilt
	 *            the object to be modified
	 * @return A new Builder instance.
	 */
	public static Builder getBuilder(User preBuilt) {
		return new Builder(preBuilt);
	}

	/**
	 * Gets the full name of the User.
	 * 
	 * @return The full name of the person.
	 */
	public String getFullName() {
		StringBuilder name = new StringBuilder();

		name.append(firstName);
		name.append(" ");
		name.append(lastName);

		return name.toString();
	}

	/**
	 * A Builder class used to create new User objects.
	 */
	public static class Builder {
		User built;

		/**
		 * Creates a new Builder instance.
		 */
		Builder() {
			built = new User();
		}

		/**
		 * Creates a new Builder instance.
		 */
		Builder(User preBuilt) {
			built = preBuilt;
		}

		/**
		 * To set the user username
		 * 
		 * @param username
		 *            the user username
		 * @return A Builder instance.
		 */
		public Builder setUsername(String username) {
			built.username = username;
			return this;
		}

		/**
		 * To set the user password
		 * 
		 * @param password
		 *            the user password
		 * @return A Builder instance.
		 */
		public Builder setPassword(String password) {
			built.password = password;
			return this;
		}

		/**
		 * To set the user first name
		 * 
		 * @param firstName
		 *            the user first name
		 * @return A Builder instance.
		 */
		public Builder setFirstName(String firstName) {
			built.firstName = firstName;
			return this;
		}

		/**
		 * To set the user last name
		 * 
		 * @param lastName
		 *            the user last name
		 * @return A Builder instance.
		 */
		public Builder setLastName(String lastName) {
			built.lastName = lastName;
			return this;
		}

		/**
		 * To set the user department
		 * 
		 * @param department
		 *            the user department
		 * @return A Builder instance.
		 */
		public Builder setDepartment(Department department) {
			built.department = department;
			return this;
		}
		
		/**
		 * To set the user role
		 * 
		 * @param department
		 *            the user role
		 * @return A Builder instance.
		 */
		public Builder setRole(Role role) {
			if(built.roles == null)
				built.roles = new ArrayList<Role>();
			built.roles.add(role);
			return this;
		}

		/**
		 * Builds the new User object.
		 * 
		 * @return The created User object.
		 */
		public User build() {
			return built;
		}
	}

	public Long getUserId() {
		return userId;
	}

	public String getUsername() {
		return username;
	}

	public String getPassword() {
		return password;
	}

	public String getFirstName() {
		return firstName;
	}

	public String getLastName() {
		return lastName;
	}

	public String getEmail() {
		return email;
	}

	@Override
	public String toString() {
		return ToStringBuilder.reflectionToString(this);
	}
}