Glassfish example source code file (Pager.java)

This example Glassfish source code file (Pager.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Glassfish tags/keywords

bufferedreader, bufferedreader, bufferedwriter, bufferedwriter, io, ioexception, ioexception, pager, pager, reader, string, writer

The Glassfish Pager.java source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package com.sun.enterprise.admin.cli;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;

/**
 * Pager.java
 *
 * @author <a href="mailto:toby.h.ferguson@sun.com">Toby H Ferguson
 */

class Pager {
    private BufferedReader in;
    private BufferedWriter out;
    private int pageLength;
    private String line;

    /**
     * Construct an object which will copy one pages worth of lines
     * at a time from the input to the
     * the output.
     *
     * No attempt is made under any circumstances to close the input
     * or output.
     *
     * @param lines the number of lines in a page. A number less
     * than 0 means copy all the input to the output.
     * @param in the source of the copy operation
     * @param out the destination of the copy operation
     * @throws IOException if there's a problem reading from, or
     * writing to, the source or destination
     */
    Pager(int lines, Reader in, Writer out) throws IOException {
        this.in = new BufferedReader(in);
        this.out = new BufferedWriter(out);
        pageLength = lines;
        nextLine();
    }

    /**
     * Copy the next page worth of lines from input to output
     */
    void nextPage() throws IOException {
        for (int i = 0; (pageLength < 0 || i < pageLength) && hasNext(); i++) {
            out.write(line);
            out.newLine();
            nextLine();
        }
        out.flush();
    }

    /**
     * Indicate if there are lines left to be copied
     * @return true iff there is at least one line left to be copied
     */
    boolean hasNext() {
        return line != null;
    }

    /**
     * Get the next line and copy it inot the internal buffer so's
     * we can answer the hasNext() question
     */
    private void nextLine() throws IOException {
        line = in.readLine();
    }
}