Java tutorial
/* * Copyright 2014 The Netty Project * * The Netty Project licenses this file to you 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. */ package io.netty.handler.codec.mqtt; import io.netty.util.internal.StringUtil; /** * Variable Header containing only Message Id * See <a href="http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.html#msg-id">MQTTV3.1/msg-id</a> */ public final class MqttMessageIdVariableHeader { private final int messageId; public static MqttMessageIdVariableHeader from(int messageId) { if (messageId < 1 || messageId > 0xffff) { throw new IllegalArgumentException("messageId: " + messageId + " (expected: 1 ~ 65535)"); } return new MqttMessageIdVariableHeader(messageId); } private MqttMessageIdVariableHeader(int messageId) { this.messageId = messageId; } public int messageId() { return messageId; } @Override public String toString() { return new StringBuilder(StringUtil.simpleClassName(this)).append('[').append("messageId=") .append(messageId).append(']').toString(); } }