com.b2international.snowowl.core.domain.CollectionResource.java Source code

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Here is the source code for com.b2international.snowowl.core.domain.CollectionResource.java

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/*
 * Copyright 2011-2017 B2i Healthcare Pte Ltd, http://b2i.sg
 * 
 * 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 com.b2international.snowowl.core.domain;

import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.stream.Stream;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;

/**
 * Represents a collection resource in the RESTful API.
 * 
 * @since 4.0
 */
public class CollectionResource<T> implements Serializable, Iterable<T> {

    private static final long serialVersionUID = -840552452105348114L;

    private final List<T> items;

    protected CollectionResource(List<T> items) {
        this.items = items == null ? Collections.<T>emptyList() : items;
    }

    /**
     * @return <tt>true</tt> if this {@link CollectionResource} contains no elements
     * @since 5.8 
     */
    @JsonIgnore
    public final boolean isEmpty() {
        return getItems().isEmpty();
    }

    /**
     * @return the items associated in the collection.
     */
    public final List<T> getItems() {
        return items;
    }

    @Override
    public Iterator<T> iterator() {
        return items.iterator();
    }

    /**
     * Creates a new {@link CollectionResource} for the given items.
     * 
     * @param items
     * @return
     */
    public static <T> CollectionResource<T> of(List<T> items) {
        return new CollectionResource<T>(items);
    }

    /**
     * Creates a new {@link CollectionResource} for the given items.
     * 
     * @param items
     * @return
     */
    @JsonCreator
    public static <T> CollectionResource<T> of(@JsonProperty("items") Collection<T> items) {
        if (items instanceof List) {
            return of((List<T>) items);
        }
        return of(ImmutableList.copyOf(items));
    }

    @Override
    public String toString() {
        return Objects.toStringHelper(CollectionResource.class).add("items", getItems()).toString();
    }

    /**
     * @return an {@link Optional} item in this collection resource
     */
    @JsonIgnore
    public Optional<T> first() {
        return Optional.ofNullable(Iterables.getFirst(getItems(), null));
    }

    /**
     * Returns a sequential {@code Stream} with this collection resource as its source.
     * @return a {@link Stream} over the items of this collection resource
     * @since 6.0
     */
    @JsonIgnore
    public Stream<T> stream() {
        return getItems().stream();
    }

}