org.apache.tools.ant.util.LazyHashtable 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.tools.ant.util;
import java.util.Enumeration;
import java.util.Hashtable;
/** Hashtable implementation that allows delayed construction
* of expensive objects
*
* All operations that need access to the full list of objects
* will call initAll() first. Get and put are cheap.
*
* @since Ant 1.6
*/
public class LazyHashtable extends Hashtable {
// CheckStyle:VisibilityModifier OFF - bc
protected boolean initAllDone = false;
// CheckStyle:VisibilityModifier OFF - bc
/** No arg constructor. */
public LazyHashtable() {
super();
}
/** Used to be part of init. It must be done once - but
* we delay it until we do need _all_ tasks. Otherwise we
* just get the tasks that we need, and avoid costly init.
*/
protected void initAll() {
if (initAllDone) {
return;
}
initAllDone = true;
}
/**
* Get a enumeration over the elements.
* @return an enumeration.
*/
public Enumeration elements() {
initAll();
return super.elements();
}
/**
* Check if the table is empty.
* @return true if it is.
*/
public boolean isEmpty() {
initAll();
return super.isEmpty();
}
/**
* Get the size of the table.
* @return the size.
*/
public int size() {
initAll();
return super.size();
}
/**
* Check if the table contains a particular value.
* @param value the value to look for.
* @return true if the table contains the value.
*/
public boolean contains(Object value) {
initAll();
return super.contains(value);
}
/**
* Check if the table contains a particular key.
* @param value the key to look for.
* @return true if the table contains key.
*/
public boolean containsKey(Object value) {
initAll();
return super.containsKey(value);
}
/**
* Delegates to {@link #contains contains}.
* @param value the value to look for.
* @return true if the table contains the value.
*/
public boolean containsValue(Object value) {
return contains(value);
}
/**
* Get an enumeration over the keys.
* @return an enumeration.
*/
public Enumeration keys() {
initAll();
return super.keys();
}
// TODO Unfortunately JDK1.2 adds entrySet(), keySet(), values() -
// implementing this requires a small hack, we can add it later.
}