Java tutorial
/* * 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.druid.common.utils; import com.google.common.base.Joiner; import com.google.common.base.Strings; import org.apache.druid.java.util.common.StringUtils; import java.util.ArrayList; import java.util.UUID; /** * */ public class UUIDUtils { public static final String UUID_DELIM = "_"; /** * Generates a universally unique identifier. * * @param extraData Extra data which often takes the form of debugging information * * @return A string which is a universally unique id (as determined by java.util.UUID) with extra data. It does not conform to a UUID variant standard. */ public static String generateUuid(String... extraData) { String extra = null; if (extraData != null && extraData.length > 0) { final ArrayList<String> extraStrings = new ArrayList<>(extraData.length); for (String extraString : extraData) { if (!Strings.isNullOrEmpty(extraString)) { extraStrings.add(extraString); } } if (!extraStrings.isEmpty()) { extra = Joiner.on(UUID_DELIM).join(extraStrings); } } // We don't use "-" in general, so remove them here. final String uuid = StringUtils.removeChar(UUID.randomUUID().toString(), '-'); return extra == null ? uuid : (extra + UUID_DELIM + uuid); } }