Returns an instance of the given class name, by calling the default constructor. : Class Method Field Name « Reflection « Java

1. Java
2. Reflection
3. Class Method Field Name

Returns an instance of the given class name, by calling the default constructor.

 
/*
 * $Id: ClassUtil.java 709153 2008-10-30 12:54:10Z apetrelli $
 *
 * 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.
 */



/**
 * Utilities to work with dynamic class loading and instantiation.
 *
 * @version $Rev: 709153 $ $Date: 2008-10-30 13:54:10 +0100 (Thu, 30 Oct 2008) $
 * @since 2.0.7
 */
public class Main {

  /**
   * Returns an instance of the given class name, by calling the default
   * constructor.
   *
   * @param className The class name to load and to instantiate.
   * @param returnNull If <code>true</code>, if the class is not found it
   * returns <code>true</code>, otherwise it throws a
   * <code>TilesException</code>.
   * @return The new instance of the class name.
   * @throws CannotInstantiateObjectException If something goes wrong during instantiation.
   * @since 2.0.7
   */
  public static Object instantiate(String className, boolean returnNull) {
      ClassLoader original = Thread.currentThread().getContextClassLoader();
      if (original == null) {
          Thread.currentThread().setContextClassLoader(Main.class.getClassLoader());
      }
      try {
          Class<?> namedClass = Class.forName(className);
          return namedClass.newInstance();
      } catch (ClassNotFoundException e) {
          if (returnNull) {
              return null;
          }
          throw new RuntimeException(
                  "Unable to resolve factory class: '" + className + "'", e);
      } catch (IllegalAccessException e) {
          throw new RuntimeException(
                  "Unable to access factory class: '" + className + "'", e);
      } catch (InstantiationException e) {
          throw new RuntimeException(
                  "Unable to instantiate factory class: '"
                          + className
                          + "'. Make sure that this class has a default constructor",
                  e);
      } finally {
          // If the original context classloader of the current thread was
          // null, it must be reset.
          if (original == null) {
              Thread.currentThread().setContextClassLoader(null);
          }
      }
  }

}

   
  

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