Link.java

/*
 * Copyright 2012 Guido Steinacker
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.otto.jsonhome.registry.store;

import java.net.URI;

/**
 * A link to a resource, consisting of a title and href.
 *
 * @author Guido Steinacker
 * @since 14.11.12
 */
public final class Link {

    private final String title;
    private final URI href;

    /**
     * Creates a new link to a resource.
     *
     * @param href the URI of the linked json-home document.
     * @param title the title of the link.
     */
    public Link(final URI href,
                final String title) {
        if (href == null) {
            throw new NullPointerException("'href' must not be null.");
        }
        if (!href.isAbsolute()) {
            throw new IllegalArgumentException("'href' must be an absolute URI.");
        }
        this.title = title != null ? title : "";
        this.href = href;
    }

    /**
     * Title of the system offering the json-home document.
     *
     * @return String
     */
    public String getTitle() {
        return title;
    }

    /**
     * The URI of the referred json-home document.
     *
     * @return absolute URI.
     */
    public URI getHref() {
        return href;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Link link = (Link) o;

        if (href != null ? !href.equals(link.href) : link.href != null) return false;
        if (title != null ? !title.equals(link.title) : link.title != null) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = title != null ? title.hashCode() : 0;
        result = 31 * result + (href != null ? href.hashCode() : 0);
        return result;
    }

    @Override
    public String toString() {
        return "Link{" +
                "title='" + title + '\'' +
                ", href=" + href +
                '}';
    }
}