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.lens.cube.error; import static com.google.common.base.Preconditions.checkArgument; import static com.google.common.base.Preconditions.checkState; import java.io.Serializable; import java.util.*; import javax.xml.bind.annotation.*; import org.apache.commons.lang.StringUtils; import lombok.*; @XmlRootElement @XmlAccessorType(XmlAccessType.FIELD) @NoArgsConstructor(access = AccessLevel.PACKAGE) @EqualsAndHashCode @ToString public class ConflictingFields implements Serializable { private static final String SEP = ", "; @XmlElementWrapper(name = "conflictingFields") @XmlElement(name = "field") private SortedSet<String> fields; public ConflictingFields(@NonNull final SortedSet<String> fields) { checkArgument(!fields.isEmpty(), "We should atleast have one conflicting field to create a valid instance."); for (String field : fields) { checkState(field != null, "Conflicting fields must not contain null. Conflicting fields: %s", fields); } this.fields = fields; } public String getConflictingFieldsString() { String conflictingFieldsStrJoined = StringUtils.join(fields, SEP); if (fields.size() == 1) { return conflictingFieldsStrJoined + " cannot be queried"; } else { return conflictingFieldsStrJoined + " cannot be queried together"; } } }