Java example source code file (AttributeKey.java)

This example Java source code file (AttributeKey.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractconstant, attributekey, constantpool, override, string, suppresswarnings, unuseddeclaration

The AttributeKey.java Java example source code

/*
 * 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;

/**
 * Key which can be used to access {@link Attribute} out of the {@link AttributeMap}. Be aware that it is not be
 * possible to have multiple keys with the same name.
 *
 * @param <T>   the type of the {@link Attribute} which can be accessed via this {@link AttributeKey}.
 */
@SuppressWarnings("UnusedDeclaration") // 'T' is used only at compile time
public final class AttributeKey<T> extends AbstractConstant> {

    private static final ConstantPool<AttributeKey pool = new ConstantPool>() {
        @Override
        protected AttributeKey<Object> newConstant(int id, String name) {
            return new AttributeKey<Object>(id, name);
        }
    };

    /**
     * Returns the singleton instance of the {@link AttributeKey} which has the specified {@code name}.
     */
    @SuppressWarnings("unchecked")
    public static <T> AttributeKey valueOf(String name) {
        return (AttributeKey<T>) pool.valueOf(name);
    }

    /**
     * Returns {@code true} if a {@link AttributeKey} exists for the given {@code name}.
     */
    public static boolean exists(String name) {
        return pool.exists(name);
    }

    /**
     * Creates a new {@link AttributeKey} for the given {@code name} or fail with an
     * {@link IllegalArgumentException} if a {@link AttributeKey} for the given {@code name} exists.
     */
    @SuppressWarnings("unchecked")
    public static <T> AttributeKey newInstance(String name) {
        return (AttributeKey<T>) pool.newInstance(name);
    }

    @SuppressWarnings("unchecked")
    public static <T> AttributeKey valueOf(Class firstNameComponent, String secondNameComponent) {
        return (AttributeKey<T>) pool.valueOf(firstNameComponent, secondNameComponent);
    }

    private AttributeKey(int id, String name) {
        super(id, name);
    }
}