/*
 * Java Genetic Algorithm Library (@__identifier__@).
 * Copyright (c) @__year__@ Franz Wilhelmstötter
 *
 * Licensed 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.
 *
 * Author:
 *    Franz Wilhelmstötter (franz.wilhelmstoetter@gmx.at)
 */
package org.jenetics.internal.util;

import static java.util.Objects.requireNonNull;

import java.util.function.Supplier;

/**
 * @author <a href="mailto:franz.wilhelmstoetter@gmx.at">Franz Wilhelmstötter</a>
 * @since 3.0
 * @version 3.0 &mdash; <em>$Date: 2014-09-05 $</em>
 */
public class Lazy<T> {

	private final Supplier<T> _supplier;
	private T _value = null;

	private Lazy(final Supplier<T> supplier) {
		_supplier = requireNonNull(supplier);
	}

	public synchronized T get() {
		if (_value == null) {
			_value = _supplier.get();
		}

		return _value;
	}

	public static <T> Lazy<T> of(final Supplier<T> supplier) {
		return new Lazy<>(supplier);
	}

}

@@ -816,24 +816,53 @@
 reNonNull;%0A%0A
+import java.io.Serializable;%0A
 import java.
@@ -1064,17 +1064,104 @@
 Lazy%3CT%3E 
-%7B
+implements Supplier%3CT%3E, Serializable %7B%0A%09private static final long serialVersionUID = 1L;
 %0A%0A%09priva
@@ -1192,16 +1192,17 @@
 pplier;%0A
+%0A
 %09private
@@ -1214,15 +1214,54 @@
 alue
- = null
+;%0A%09private volatile boolean _evaluated = false
 ;%0A%0A%09
@@ -1348,22 +1348,99 @@
 );%0A%09%7D%0A%0A%09
-public
+@Override%0A%09public T get() %7B%0A%09%09return _evaluated ? _value : evaluate();%0A%09%7D%0A%0A%09private
  synchro
@@ -1447,19 +1447,24 @@
 nized T 
-get
+evaluate
 () %7B%0A%09%09i
@@ -1470,22 +1470,19 @@
 if (
-_
+!_e
 valu
-e == null
+ated
 ) %7B%0A
@@ -1510,16 +1510,38 @@
 .get();%0A
+%09%09%09_evaluated = true;%0A
 %09%09%7D%0A%0A%09%09r

Implement 'Lazy' evaluation class.