Java tutorial
/* * Copyright 2006-2019 the original author or authors. * * 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 * * https://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 org.springframework.batch.item.support; import java.util.Iterator; import org.springframework.batch.item.ItemReader; import org.springframework.util.Assert; /** * An {@link ItemReader} that pulls data from a {@link Iterator} or * {@link Iterable} using the constructors. * * @author Juliusz Brzostek * @author Dave Syer * @author Mahmoud Ben Hassine */ public class IteratorItemReader<T> implements ItemReader<T> { /** * Internal iterator */ private final Iterator<T> iterator; /** * Construct a new reader from this iterable (could be a collection), by * extracting an instance of {@link Iterator} from it. * * @param iterable in instance of {@link Iterable} * * @see Iterable#iterator() */ public IteratorItemReader(Iterable<T> iterable) { Assert.notNull(iterable, "Iterable argument cannot be null!"); this.iterator = iterable.iterator(); } /** * Construct a new reader from this iterator directly. * @param iterator an instance of {@link Iterator} */ public IteratorItemReader(Iterator<T> iterator) { Assert.notNull(iterator, "Iterator argument cannot be null!"); this.iterator = iterator; } /** * Implementation of {@link ItemReader#read()} that just iterates over the * iterator provided. */ @Override public T read() { if (iterator.hasNext()) return iterator.next(); else return null; // end of data } }