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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 <a href="http://mina.apache.org">Apache MINA Project</a>
    27   */
    28  public class TennisBall {
    29      private final boolean ping;
    30
    31      private final int ttl;
    32
    33      /**
    34       * Creates a new ball with the specified TTL (Time To Live) value.
    35       */
    36      public TennisBall(int ttl) {
    37          this(ttl, true);
    38      }
    39
    40      /**
    41       * Creates a new ball with the specified TTL value and PING/PONG state.
    42       */
    43      private TennisBall(int ttl, boolean ping) {
    44          this.ttl = ttl;
    45          this.ping = ping;
    46      }
    47
    48      /**
    49       * Returns the TTL value of this ball.
    50       */
    51      public int getTTL() {
    52          return ttl;
    53      }
    54
    55      /**
    56       * Returns the ball after {@link TennisPlayer}'s stroke.
    57       * The returned ball has decreased TTL value and switched PING/PONG state.
    58       */
    59      public TennisBall stroke() {
    60          return new TennisBall(ttl - 1, !ping);
    61      }
    62
    63      /**
    64       * Returns string representation of this message (<code>[PING|PONG]
    65       * (TTL)</code>).
    66       */
    67      @Override
    68      public String toString() {
    69          if (ping) {
    70              return "PING (" + ttl + ")";
    71          } else {
    72              return "PONG (" + ttl + ")";
    73          }
    74      }
    75  }