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The Spring Batch Infrastructure is a set of low-level components, interfaces and tools for batch processing applications and optimisations.

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/*
 * Copyright 2006-2018 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;

import org.springframework.lang.Nullable;

/**
 * 

* A specialisation of {@link ItemReader} that allows the user to look ahead * into the stream of items. This is useful, for instance, when reading flat * file data that contains record separator lines which are actually part of the * next record. *

* *

* The detailed contract for {@link #peek()} has to be defined by the * implementation because there is no general way to define it in a concurrent * environment. The definition of "the next read()" operation is tenuous if * multiple clients are reading concurrently, and the ability to peek implies * that some state is likely to be stored, so implementations of * {@link PeekableItemReader} may well be restricted to single threaded use. *

* * @author Dave Syer * @author Mahmoud Ben Hassine * */ public interface PeekableItemReader extends ItemReader { /** * Get the next item that would be returned by {@link #read()}, without * affecting the result of {@link #read()}. * * @return the next item or {@code null} if the data source is exhausted * @throws Exception if there is a problem */ @Nullable T peek() throws Exception, UnexpectedInputException, ParseException; }




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