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Hadoop is the distributed computing framework of Apache; hadoop-core contains
the filesystem, job tracker and map/reduce modules
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/** * 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.apache.hadoop.util; import java.lang.reflect.Array; import java.util.List; /** * Contains utility methods for dealing with Java Generics. */ public class GenericsUtil { /** * Returns the Class object (of type
to a an array of *Class<T>
) of the * argument of typeT
. * @paramThe type of the argument * @param t the object to get it class * @return Class<T>
*/ public staticClass getClass(T t) { @SuppressWarnings("unchecked") Class clazz = (Class )t.getClass(); return clazz; } /** * Converts the given List<T>
to a an array of *T[]
. * @param c the Class object of the items in the list * @param list the list to convert */ public staticT[] toArray(Class c, List list) { @SuppressWarnings("unchecked") T[] ta= (T[])Array.newInstance(c, list.size()); for (int i= 0; i List<T> T[]
. * @param list the list to convert * @throws ArrayIndexOutOfBoundsException if the list is empty. * Use {@link #toArray(Class, List)} if the list may be empty. */ public staticT[] toArray(List list) { return toArray(getClass(list.get(0)), list); } }