Java tutorial
package bigbluej; /* * 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. */ import org.apache.commons.lang.ArrayUtils; import org.apache.commons.lang.StringUtils; import org.apache.commons.lang.Validate; /** * @author Michael Lieshoff */ public class DocumentCommand { private final String url; private final String name; private final byte[] content; private DocumentCommand(String url, String name, byte[] content) { if (StringUtils.isNotBlank(url)) { Validate.isTrue(ArrayUtils.isEmpty(content), "when set url, don't set content too!"); Validate.isTrue(StringUtils.isBlank(name), "when set url, don't set name too!"); } else if (StringUtils.isNotBlank(name)) { Validate.isTrue(ArrayUtils.isNotEmpty(content), "when set name, set content too!"); Validate.isTrue(StringUtils.isBlank(url), "when set name, don't set url too!"); } else { throw new IllegalArgumentException("set either name or url!"); } this.url = url; this.name = name; this.content = content; } public static Builder builder() { return new Builder(); } public String getUrl() { return url; } public String getName() { return name; } public byte[] getContent() { return content; } public static class Builder { private String url; private String name; private byte[] content; private Builder() { } public DocumentCommand build() { return new DocumentCommand(url, name, content); } public Builder url(String url) { this.url = url; return this; } public Builder name(String name) { this.name = name; return this; } public Builder content(byte[] content) { this.content = content; return this; } } }