001//////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code for adherence to a set of rules. 003// Copyright (C) 2001-2015 the original author or authors. 004// 005// This library is free software; you can redistribute it and/or 006// modify it under the terms of the GNU Lesser General Public 007// License as published by the Free Software Foundation; either 008// version 2.1 of the License, or (at your option) any later version. 009// 010// This library is distributed in the hope that it will be useful, 011// but WITHOUT ANY WARRANTY; without even the implied warranty of 012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013// Lesser General Public License for more details. 014// 015// You should have received a copy of the GNU Lesser General Public 016// License along with this library; if not, write to the Free Software 017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018//////////////////////////////////////////////////////////////////////////////// 019 020package com.puppycrawl.tools.checkstyle; 021 022import java.util.Properties; 023 024/** 025 * Resolves external properties from an 026 * underlying {@code Properties} object. 027 * 028 * @author lkuehne 029 */ 030public final class PropertiesExpander 031 implements PropertyResolver { 032 /** The underlying Properties object. */ 033 private final Properties properties = new Properties(); 034 035 /** 036 * Creates a new PropertiesExpander. 037 * @param properties the underlying properties to use for 038 * property resolution. 039 * @throws IllegalArgumentException indicates null was passed 040 * @noinspection CollectionDeclaredAsConcreteClass 041 */ 042 public PropertiesExpander(Properties properties) { 043 if (properties == null) { 044 throw new IllegalArgumentException("cannot pass null"); 045 } 046 this.properties.putAll(properties); 047 } 048 049 @Override 050 public String resolve(String name) { 051 return properties.getProperty(name); 052 } 053}