Java Collection to Array toBaseTypedCollection(Collection initial)

Description

Workaround for compile time checking of list types.

License

Apache License

Parameter

Parameter	Description
initial	the wildcard collection
T	the type constraint for the target collection

Return

if initial is null, null otherwise the new, type constrained collection

Declaration

@SuppressWarnings("unchecked")
public static <T> Collection<T> toBaseTypedCollection(Collection<? extends T> initial) 

Method Source Code

//package com.java2s;
/*/*from w w w  . j  ava2s  .  c  o m*/
 * 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.
 */

import java.util.Collection;

public class Main {
    /**
     * Workaround for compile time checking of list types.  Generics are not persisted through runtime.  The compile time
     * type system will still check that the items are castable to the base type.
     * @param initial the wildcard collection
     * @param <T> the type constraint for the target collection
     * @return if initial is null, null otherwise the new, type constrained collection
     */
    @SuppressWarnings("unchecked")
    public static <T> Collection<T> toBaseTypedCollection(Collection<? extends T> initial) {
        return (Collection<T>) initial;
    }
}

Related

1. toArray(java.util.Collection collection)
2. toArray(T arrayOrCollection)
3. toArrayInt(Collection integerCollection)
4. toArrays(Collection strings)
5. toArrayString(Collection col, boolean spacing)
6. toByteArray(Collection c)
7. toByteArray(Collection c)
8. toCharArray(Collection source)
9. toCharArray(Collection patterns)