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    1   /*
    2    *  Licensed to the Apache Software Foundation (ASF) under one
    3    *  or more contributor license agreements.  See the NOTICE file
    4    *  distributed with this work for additional information
    5    *  regarding copyright ownership.  The ASF licenses this file
    6    *  to you under the Apache License, Version 2.0 (the
    7    *  "License"); you may not use this file except in compliance
    8    *  with the License.  You may obtain a copy of the License at
    9    *
    10   *    http://www.apache.org/licenses/LICENSE-2.0
    11   *
    12   *  Unless required by applicable law or agreed to in writing,
    13   *  software distributed under the License is distributed on an
    14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    15   *  KIND, either express or implied.  See the License for the
    16   *  specific language governing permissions and limitations
    17   *  under the License.
    18   *
    19   */
    20  package org.apache.mina.example.tennis;
    21
    22  /**
    23   * A tennis ball which has TTL value and state whose value is one of 'PING' and
    24   * 'PONG'.
    25   *
    26   * @author The Apache Directory Project (mina-dev@directory.apache.org)
    27   * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (Fri, 13 Jul 2007) $
    28   */
    29  public class TennisBall {
    30      private final boolean ping;
    31
    32      private final int ttl;
    33
    34      /**
    35       * Creates a new ball with the specified TTL (Time To Live) value.
    36       */
    37      public TennisBall(int ttl) {
    38          this(ttl, true);
    39      }
    40
    41      /**
    42       * Creates a new ball with the specified TTL value and PING/PONG state.
    43       */
    44      private TennisBall(int ttl, boolean ping) {
    45          this.ttl = ttl;
    46          this.ping = ping;
    47      }
    48
    49      /**
    50       * Returns the TTL value of this ball.
    51       */
    52      public int getTTL() {
    53          return ttl;
    54      }
    55
    56      /**
    57       * Returns the ball after {@link TennisPlayer}'s stroke.
    58       * The returned ball has decreased TTL value and switched PING/PONG state.
    59       */
    60      public TennisBall stroke() {
    61          return new TennisBall(ttl - 1, !ping);
    62      }
    63
    64      /**
    65       * Returns string representation of this message (<code>[PING|PONG]
    66       * (TTL)</code>).
    67       */
    68      public String toString() {
    69          if (ping) {
    70              return "PING (" + ttl + ")";
    71          } else {
    72              return "PONG (" + ttl + ")";
    73          }
    74      }
    75  }