com.groupbyinc.common.apache.commons.text.lookup.EnvironmentVariableStringLookup Maven / Gradle / Ivy
/*
* 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.commons.text.lookup;
/**
* Looks up keys from environment variables.
*
* @since 1.3
*/
final class EnvironmentVariableStringLookup extends AbstractStringLookup {
/**
* Defines the singleton for this class.
*/
static final EnvironmentVariableStringLookup INSTANCE = new EnvironmentVariableStringLookup();
/**
* No need to build instances for now.
*/
private EnvironmentVariableStringLookup() {
// empty
}
/**
* Looks up the value of the given environment variable.
*
* @param key
* the key to be looked up, may be null
* @return The value of the environment variable.
* @see System#getenv(String)
*/
@Override
public String lookup(final String key) {
// getenv throws NullPointerException if name is null
return key != null ? System.getenv(key) : null;
}
}