Account.java

package de.japrost.jabudget.domain.account;

import static java.util.Objects.requireNonNull;

import java.io.Serializable;
import java.util.Objects;
import java.util.Optional;

/**
 * An account in JaBudGet.<br>
 * The Account is identified by its id.
 */
public class Account implements Serializable {

    private static final long serialVersionUID = 1L;
    private final String id;
    private String name;

    /**
     * Create an account.
     *
     * @param id the id. MUST NOT be {@code null}.
     */
    public Account(final String id) {
        requireNonNull(id, "'id' MUST NOT be null.");
        this.id = id;
    }

    /**
     * Gets the identity of the Account.
     *
     * @return the identity of an Account.
     */
    public String getId() {
        return id;
    }

    /**
     * Gets the given name of the Account.
     *
     * @return the given name. If no name is given returns an empty String.
     */
    public String getName() {
        if (Objects.nonNull(name)) {
            return name;
        } else {
            return "";
        }
    }

    /**
     * Sets the given name of the Account.
     *
     * @param name the new given name. SHOULD NOT BE {@code null}.
     */
    public void setName(final String name) {
        this.name = name;
    }

    /**
     * {@inheritDoc}
     * <p>
     * <strong>This implementation</strong> uses just {@link Account#id}.
     */
    @Override
    public int hashCode() {
        return id.hashCode();
    }

    /**
     * {@inheritDoc}
     * <p>
     * <strong>This implementation</strong> uses just {@link Account#id}.
     */
    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Account other = (Account) obj;
        if (!id.equals(other.id)) {
            return false;
        }
        return true;
    }

    /**
     * {@inheritDoc}
     * <p>
     * <strong>This implementation</strong> shows all fields.
     */
    @Override
    public String toString() {
        final StringBuilder builder = new StringBuilder();
        builder.append("Account [id=").append(id).append(", name=").append(name).append("]");
        return builder.toString();
    }

    /**
     * Builder for {@link Account}s.
     */
    public static class Builder {

        private String id;
        private String name;

        /**
         * Create an empty account builder.
         */
        public Builder() {
        }

        /**
         * Create an account builder with all required fields.
         *
         * @param id the id. MUST NOT be {@code null}.
         */
        public Builder(final String id) {
            this.id = id;
        }

        /**
         * Create an account builder by example;
         *
         * @param account the example account. MAY BE {@code null}.
         */
        public Builder(final Account account) {
            if (account != null) {
                this.id = account.id;
                this.name = account.name;
            }
        }

        /**
         * Create an empty account builder.
         *
         * @return the {@link Builder}.
         */
        public static Builder builder() {
            return new Builder();
        }

        /**
         * Create an account builder with all required fields.
         *
         * @param id the id. MUST NOT be {@code null}.
         * @return the {@link Builder}.
         */
        public static Builder builder(final String id) {
            return new Builder(id);
        }

        /**
         * Create an account builder by example;
         *
         * @param account the example account.
         * @return the {@link Builder}.
         */
        public static Builder builder(final Account account) {
            return new Builder(account);
        }

        /**
         * Build the account.
         *
         * @return a new account instance.
         */
        public Account build() {
            final Account result = new Account(id);
            result.name = name;
            return result;
        }

        /**
         * Build the account if it would be valid.
         *
         * @return a new account instance or an empty optional.
         */
        public Optional<Account> buildOptional() {
            if (id == null) {
                return Optional.empty();
            }
            final Account result = new Account(id);
            result.name = name;
            return Optional.of(result);
        }

        /**
         * Sets the id of an Account. MUST NOT be {@code null}.
         *
         * @param id the id of an Account
         * @return this
         */
        public Builder setId(final String id) {
            this.id = id;
            return this;
        }

        /**
         * Sets the given name of an Account.
         *
         * @param name the new given name of an Account
         * @return this
         */
        public Builder setName(final String name) {
            this.name = name;
            return this;
        }
    }
}