org.springframework.batch.item.support.IteratorItemReader Maven / Gradle / Ivy
/*
* 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.lang.Nullable;
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 implements ItemReader {
/**
* Internal iterator
*/
private final Iterator 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 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 iterator) {
Assert.notNull(iterator, "Iterator argument cannot be null!");
this.iterator = iterator;
}
/**
* Implementation of {@link ItemReader#read()} that just iterates over the
* iterator provided.
*/
@Nullable
@Override
public T read() {
if (iterator.hasNext())
return iterator.next();
else
return null; // end of data
}
}