/*
* 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.eigenbase.util;
/**
* A mutable slot that can contain one object.
*
* <p>A holder is useful for implementing OUT or IN-OUT parameters.</p>
*
* <p>It is possible to sub-class to receive events on get or set.</p>
*
* @param <E> Element type
*/
public class Holder<E> {
private E e;
/** Creates a Holder containing a given value.
*
* <p>Call this method from a derived constructor or via the {@link #of}
* method. */
protected Holder(E e) {
this.e = e;
}
/** Sets the value. */
public void set(E e) {
this.e = e;
}
/** Gets the value. */
public E get() {
return e;
}
/** Creates a holder containing a given value. */
public static <E> Holder<E> of(E e) {
return new Holder<E>(e);
}
}
// End Holder.java