opennlp.tools.util.jvm.StringInterners 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 opennlp.tools.util.jvm;
import java.lang.reflect.Constructor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Provides string interning utility methods. Interning mechanism can be configured via the
* system property {@code opennlp.interner.class} by specifying an implementation via its
* fully qualified classname. It needs to implement {@link StringInterner}.
*
* If not specified by the user, the default interner is {@link CHMStringInterner}.
*/
public class StringInterners {
private static final Logger LOGGER = LoggerFactory.getLogger(StringInterners.class);
private static final StringInterner INTERNER;
static {
final String clazzName = System.getProperty("opennlp.interner.class",
CHMStringInterner.class.getCanonicalName());
try {
final Class clazz = Class.forName(clazzName);
final Constructor cons = clazz.getDeclaredConstructor();
INTERNER = (StringInterner) cons.newInstance();
LOGGER.debug("Using '{}' as String interner implementation.", clazzName);
} catch (Exception e) {
throw new RuntimeException("Could not load specified String interner implementation: '"
+ clazzName + "'. Reason: " + e.getLocalizedMessage(), e);
}
}
/**
* Interns and returns a reference to the representative instance
* for any collection of string instances that are equal to each other.
*
* @param sample string instance to be interned
* @return reference to the interned string instance
*/
public static String intern(String sample) {
if (sample == null) {
return null;
}
return INTERNER.intern(sample);
}
}