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 * @param ttl The time to live
37 */
38 public TennisBall(int ttl) {
39 this(ttl, true);
40 }
41
42 /**
43 * Creates a new ball with the specified TTL value and PING/PONG state.
44 */
45 private TennisBall(int ttl, boolean ping) {
46 this.ttl = ttl;
47 this.ping = ping;
48 }
49
50 /**
51 * @return the TTL value of this ball.
52 */
53 public int getTTL() {
54 return ttl;
55 }
56
57 /**
58 * @return the ball after {@link TennisPlayer}'s stroke.
59 * The returned ball has decreased TTL value and switched PING/PONG state.
60 */
61 public TennisBall stroke() {
62 return new TennisBall(ttl - 1, !ping);
63 }
64
65 /**
66 * @return string representation of this message (<code>[PING|PONG]
67 * (TTL)</code>).
68 */
69 @Override
70 public String toString() {
71 if (ping) {
72 return "PING (" + ttl + ")";
73 } else {
74 return "PONG (" + ttl + ")";
75 }
76 }
77 }