ValidationState.java

/*
 * Beanfabrics Framework Copyright (C) by Michael Karneim, beanfabrics.org
 * Use is subject to license terms. See license.txt.
 */
package org.beanfabrics.validation;

/**
 * The <code>ValidationState</code> is the result of a call to
 * {@link ValidationRule#validate()} and indicates that this rule has found some
 * invalid state. It contains a human readable text message which usually is
 * reported to the application user.
 *
 * @author Michael Karneim
 */
public class ValidationState {
    private final String message;

    /**
     * Factory-method for creating a {@link ValidationState} from the specified
     * message or <code>null</code> if the message is <code>null</code>.
     *
     * @param message String
     * @return the <code>ValidationState</code> if <code>message</code> is not
     *         <code>null</code>, otherwise returns <code>null</code>
     */
    public static ValidationState create(String message) {
        if (message == null) {
            return null;
        } else {
            return new ValidationState(message);
        }
    }

    /**
     * Constructs a new instance with the given message.
     *
     * @param message the message text of this <code>ValidationState</code>
     * @throws IllegalArgumentException when message is <code>null</code>
     */
    public ValidationState(String message)
        throws IllegalArgumentException {
        if (message == null) {
            throw new IllegalArgumentException("message==null");
        }
        this.message = message;
    }

    /**
     * Returns the message for this instance.
     *
     * @return String
     */
    public String getMessage() {
        return message;
    }

    /**
     * Returns <code>true</code> when this instance is equal to the given
     * object.
     *
     * @param other Object to compare <code>this</code> instance to
     * @return boolean <code>true</code> if this instance and the given object
     *         are equal, else <code>false</code>
     */
    @Override
    public boolean equals(Object other) {
        if (other == null) {
            return false;
        }
        if (!other.getClass().equals(this.getClass())) {
            return false;
        }
        ValidationState otherState = (ValidationState)other;
        if (message == null && otherState.message == null) {
            return true;
        } else {
            return (message != null && message.equals(otherState.message));
        }
    }

    @Override
    public int hashCode() {
        int hashCode = 1;
        hashCode = 31 * hashCode + (message == null ? 0 : message.hashCode());
        return hashCode;
    }
}