EnumChoiceProvider.java

/*
 * 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 net.formio.choice;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * Default {@link ChoiceProvider} for enums that returns all values of enum type.
 * @author Radek Beran
 *
 * @param <E>
 */
public class EnumChoiceProvider<E extends Enum<E>> implements ChoiceProvider<E> {

	private final Class<E> enumClass;
	
	public EnumChoiceProvider(Class<E> enumClass) {
		if (enumClass == null) {
			throw new IllegalArgumentException("enumClass cannot be null");
		}
		this.enumClass = enumClass;
	}
	
	@Override
	public List<? extends E> getItems() {
		E[] enums = enumClass.getEnumConstants();
		return enums != null ? Arrays.asList(enums) : new ArrayList<E>();
	}
	
}