Java tutorial
/* * Copyright 2012 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.util; /** * Holds {@link Attribute}s which can be accessed via {@link AttributeKey}. * * Implementations must be Thread-safe. */ public interface AttributeMap { /** * Get the {@link Attribute} for the given {@link AttributeKey}. This method will never return null, but may return * an {@link Attribute} which does not have a value set yet. */ <T> Attribute<T> attr(AttributeKey<T> key); /** * Returns {@code true} if and only if the given {@link Attribute} exists in this {@link AttributeMap}. */ <T> boolean hasAttr(AttributeKey<T> key); }