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/*
 * Copyright (C) 2005 The Guava Authors
 *
 * 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.google.common.reflect;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;

/**
 * Static utilities relating to Java reflection.
 *
 * @since 12.0
 */
@ElementTypesAreNonnullByDefault
public final class Reflection {

  /**
   * Returns the package name of {@code clazz} according to the Java Language Specification (section
   * 6.7). Unlike {@link Class#getPackage}, this method only parses the class name, without
   * attempting to define the {@link Package} and hence load files.
   */
  public static String getPackageName(Class clazz) {
    return getPackageName(clazz.getName());
  }

  /**
   * Returns the package name of {@code classFullName} according to the Java Language Specification
   * (section 6.7). Unlike {@link Class#getPackage}, this method only parses the class name, without
   * attempting to define the {@link Package} and hence load files.
   */
  public static String getPackageName(String classFullName) {
    int lastDot = classFullName.lastIndexOf('.');
    return (lastDot < 0) ? "" : classFullName.substring(0, lastDot);
  }

  /**
   * Ensures that the given classes are initialized, as described in JLS Section
   * 12.4.2.
   *
   * 

WARNING: Normally it's a smell if a class needs to be explicitly initialized, because static * state hurts system maintainability and testability. In cases when you have no choice while * interoperating with a legacy framework, this method helps to keep the code less ugly. * * @throws ExceptionInInitializerError if an exception is thrown during initialization of a class */ public static void initialize(Class... classes) { for (Class clazz : classes) { try { Class.forName(clazz.getName(), true, clazz.getClassLoader()); } catch (ClassNotFoundException e) { throw new AssertionError(e); } } } /** * Returns a proxy instance that implements {@code interfaceType} by dispatching method * invocations to {@code handler}. The class loader of {@code interfaceType} will be used to * define the proxy class. To implement multiple interfaces or specify a class loader, use {@link * Proxy#newProxyInstance}. * * @throws IllegalArgumentException if {@code interfaceType} does not specify the type of a Java * interface */ public static T newProxy(Class interfaceType, InvocationHandler handler) { checkNotNull(handler); checkArgument(interfaceType.isInterface(), "%s is not an interface", interfaceType); Object object = Proxy.newProxyInstance( interfaceType.getClassLoader(), new Class[] {interfaceType}, handler); return interfaceType.cast(object); } private Reflection() {} }





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