Java Reader copy to an Writer for a large file (over 2GB)

//package com.demo2s;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;

public class Main {
  public static void main(String[] argv) throws Exception {
  }//from   ww w.  java  2 s  .c om

  /**
   * The default buffer size to use.
   */
  private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

  /**
   * Copy chars from a large (over 2GB) <code>Reader</code> to a
   * <code>Writer</code>.
   * <p>
   * This method buffers the input internally, so there is no need to use a
   * <code>BufferedReader</code>.
   *
   * @param input
   *          the <code>Reader</code> to read from
   * @param output
   *          the <code>Writer</code> to write to
   * @return the number of characters copied
   * @throws NullPointerException
   *           if the input or output is null
   * @throws IOException
   *           if an I/O error occurs
   * @since Commons IO 1.3
   */
  public static long copyLarge(Reader input, Writer output) throws IOException {
    char[] buffer = new char[DEFAULT_BUFFER_SIZE];
    long count = 0;
    int n = 0;
    while (-1 != (n = input.read(buffer))) {
      output.write(buffer, 0, n);
      count += n;
    }
    return count;
  }

}

/*
 * 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
 *
 *     http://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.
 */