/*
 * 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
 *
 *     https://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.avro.util;

public class ClassUtils {

  private ClassUtils() {
  }

  
Loads a class using the class loader. 1. The class loader of the current
class is being used. 2. The thread context class loader is being used. If
both approaches fail, returns null.
Params:
className – The name of the class to load.
Returns:
The class or null if no class loader could load the class./**
   * Loads a class using the class loader. 1. The class loader of the current
   * class is being used. 2. The thread context class loader is being used. If
   * both approaches fail, returns null.
   *
   * @param className The name of the class to load.
   * @return The class or null if no class loader could load the class.
   */
  public static Class<?> forName(String className) throws ClassNotFoundException {
    return ClassUtils.forName(ClassUtils.class, className);
  }

  
Loads a class using the class loader. 1. The class loader of the context
class is being used. 2. The thread context class loader is being used. If
both approaches fail, returns null.
Params:
contextClass – The name of a context class to use.
className –    The name of the class to load
Returns:
The class or null if no class loader could load the class./**
   * Loads a class using the class loader. 1. The class loader of the context
   * class is being used. 2. The thread context class loader is being used. If
   * both approaches fail, returns null.
   *
   * @param contextClass The name of a context class to use.
   * @param className    The name of the class to load
   * @return The class or null if no class loader could load the class.
   */
  public static Class<?> forName(Class<?> contextClass, String className) throws ClassNotFoundException {
    Class<?> c = null;
    if (contextClass.getClassLoader() != null) {
      c = forName(className, contextClass.getClassLoader());
    }
    if (c == null && Thread.currentThread().getContextClassLoader() != null) {
      c = forName(className, Thread.currentThread().getContextClassLoader());
    }
    if (c == null) {
      throw new ClassNotFoundException("Failed to load class" + className);
    }
    return c;
  }

  
Loads a class using the class loader. 1. The class loader of the context
class is being used. 2. The thread context class loader is being used. If
both approaches fail, returns null.
Params:
classLoader – The classloader to use.
className –   The name of the class to load
Returns:
The class or null if no class loader could load the class./**
   * Loads a class using the class loader. 1. The class loader of the context
   * class is being used. 2. The thread context class loader is being used. If
   * both approaches fail, returns null.
   *
   * @param classLoader The classloader to use.
   * @param className   The name of the class to load
   * @return The class or null if no class loader could load the class.
   */
  public static Class<?> forName(ClassLoader classLoader, String className) throws ClassNotFoundException {
    Class<?> c = null;
    if (classLoader != null) {
      c = forName(className, classLoader);
    }
    if (c == null && Thread.currentThread().getContextClassLoader() != null) {
      c = forName(className, Thread.currentThread().getContextClassLoader());
    }
    if (c == null) {
      throw new ClassNotFoundException("Failed to load class" + className);
    }
    return c;
  }

  
Loads a Class from the specified ClassLoader without throwing ClassNotFoundException. 
Params:
className – 
classLoader – 
Returns:
/**
   * Loads a {@link Class} from the specified {@link ClassLoader} without throwing
   * {@link ClassNotFoundException}.
   *
   * @param className
   * @param classLoader
   * @return
   */
  private static Class<?> forName(String className, ClassLoader classLoader) {
    Class<?> c = null;
    if (classLoader != null && className != null) {
      try {
        c = Class.forName(className, true, classLoader);
      } catch (ClassNotFoundException e) {
        // Ignore and return null
      }
    }
    return c;
  }
}