yangyichao-mango commented on a change in pull request #3054: URL: https://github.com/apache/incubator-dolphinscheduler/pull/3054#discussion_r446300844
########## File path: dolphinscheduler-server/src/main/java/org/apache/dolphinscheduler/server/master/dispatch/host/assign/AbstractSelector.java ########## @@ -0,0 +1,45 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF 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 org.apache.dolphinscheduler.server.master.dispatch.host.assign; + +import org.apache.dolphinscheduler.common.utils.CollectionUtils; + +import java.util.Collection; + +/** + * AbstractSelector + */ +public abstract class AbstractSelector<T> implements Selector<T>{ + @Override + public T select(Collection<T> source) { + + if (CollectionUtils.isEmpty(source)) { + throw new IllegalArgumentException("Empty source."); + } + + /** + * if only one , return directly + */ + if (source.size() == 1) { + return (T)source.toArray()[0]; + } + return doSelect(source); + } + + protected abstract T doSelect(Collection<T> source); + +} Review comment: What is the purpose of this new `AbstractSelector<T>` class? In my opinion, interface default method will be better than abstract method if there is no clear inheritance relation. So is it better o implement `select` method in `Selector<T>` as a default method? 是否有必要新建一个 `AbstractSelector<T>` 类呢？ 个人理解，如果后续没有明显的继承关系的话，实现接口的default方法会比抽象类的方法有更多的好处。将 `select` 方法直接在 `Selector<T>` 接口中实现会不会更好一些？ ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
