Create List by Class Type - Java java.util

Java examples for java.util:List Operation

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Description

Create List by Class Type

Demo Code

/*/*w ww  .  ja  v a  2  s  .  c o m*/
 * JBoss, Home of Professional Open Source.
 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * 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.
 */
//package com.java2s;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class Main {
    public static void main(String[] argv) {
        List orig = java.util.Arrays.asList("asdf", "java2s.com");
        Class elemType = String.class;
        System.out.println(getList(orig, elemType));
    }

    static <E> List<E> getList(List<E> orig, Class<E> elemType) {
        if (orig == null || orig.isEmpty()) {
            return Collections.emptyList();
        } else if (orig.size() == 1) {
            return Collections.singletonList(orig.get(0));
        } else {
            return Collections.unmodifiableList(Arrays.asList(orig
                    .toArray(createArray(elemType, orig.size()))));
        }
    }

    @SuppressWarnings("unchecked")
    private static <E> E[] createArray(Class<E> elemType, int length) {
        return (E[]) Array.newInstance(elemType, length);
    }
}

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