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//******************************************************************************
//
// File: Stdio.java
// Package: edu.rit.io
// Unit: Class edu.rit.io.Stdio
//
// This Java source file is copyright (C) 2010 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ 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 General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************
package edu.rit.io;
import java.io.InputStream;
import java.io.PrintStream;
/**
* Class Stdio provides standard I/O streams that can be redirected on a
* per-thread basis.
*
* @author Alan Kaminsky
* @version 08-Oct-2010
*/
public class Stdio
{
// Prevent construction.
private Stdio()
{
}
// Hidden data members.
private static ThreadLocal<InputStream> in =
new ThreadLocal<InputStream>()
{
protected InputStream initialValue()
{
return System.in;
}
};
private static ThreadLocal<PrintStream> out =
new ThreadLocal<PrintStream>()
{
protected PrintStream initialValue()
{
return System.out;
}
};
private static ThreadLocal<PrintStream> err =
new ThreadLocal<PrintStream>()
{
protected PrintStream initialValue()
{
return System.err;
}
};
// Exported operations.
/**
* Get the standard input stream for the calling thread.
*
* @return Standard input stream.
*/
public static InputStream in()
{
return in.get();
}
/**
* Get the standard output stream for the calling thread.
*
* @return Standard output stream.
*/
public static PrintStream out()
{
return out.get();
}
/**
* Get the standard error stream for the calling thread.
*
* @return Standard error stream.
*/
public static PrintStream err()
{
return err.get();
}
/**
* Set the standard input stream for the calling thread. If not set, the
* default is <TT>System.in</TT>.
*
* @param stream Standard input stream.
*
* @exception NullPointerException
* (unchecked exception) Thrown if <TT>stream</TT> is null.
*/
public static void in
(InputStream stream)
{
if (stream == null)
{
throw new NullPointerException ("Stdio.in(): stream is null");
}
in.set (stream);
}
/**
* Set the standard output stream for the calling thread. If not set, the
* default is <TT>System.out</TT>.
*
* @param stream Standard output stream.
*
* @exception NullPointerException
* (unchecked exception) Thrown if <TT>stream</TT> is null.
*/
public static void out
(PrintStream stream)
{
if (stream == null)
{
throw new NullPointerException ("Stdio.out(): stream is null");
}
out.set (stream);
}
/**
* Set the standard error stream for the calling thread. If not set, the
* default is <TT>System.err</TT>.
*
* @param stream Standard error stream.
*
* @exception NullPointerException
* (unchecked exception) Thrown if <TT>stream</TT> is null.
*/
public static void err
(PrintStream stream)
{
if (stream == null)
{
throw new NullPointerException ("Stdio.err(): stream is null");
}
err.set (stream);
}
}
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