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The DSI utilities are a mishmash of classes accumulated during the last twenty years in projects developed at the DSI (Dipartimento di Scienze dell'Informazione, i.e., Information Sciences Department), now DI (Dipartimento di Informatica, i.e., Informatics Department), of the Universita` degli Studi di Milano.

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package it.unimi.dsi.io;

/*
 * DSI utilities
 *
 * Copyright (C) 2003-2020 Sebastiano Vigna
 *
 *  This library is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License as published by the Free
 *  Software Foundation; either version 3 of the License, or (at your option)
 *  any later version.
 *
 *  This library is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, see .
 *
 */

import java.io.Reader;
import java.io.Serializable;


/** End-of-stream-only reader.
 *
 * This reader will always return end-of-file on any read attempt.
 *
 * This class is a singleton. You cannot create a null reader,
 * but you can obtain an instance of this class using {@link #getInstance()}.
 *
 * @author Sebastiano Vigna
 * @since 0.9.2
 */

public class NullReader extends Reader implements Serializable {
	private static final long serialVersionUID = 1L;

	private final static NullReader INSTANCE = new NullReader();

	private NullReader() {}

	/** Returns the only instance of this class.
	 *
	 * @return the only instance of this class.
	 */
	public static NullReader getInstance() {
		return INSTANCE;
	}

	@Override
	public void close() {}

	@Override
	public int read(final char[] cbuf, final int off, final int len) {
		return -1;
	}
}