/*
 * 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 com.google.common.annotations.Beta;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;

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

  
Returns the package name of clazz according to the Java Language Specification (section 6.7). Unlike Class.getPackage, this method only parses the class name, without attempting to define the Package and hence load files. /**
   * 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 classFullName according to the Java Language Specification (section 6.7). Unlike Class.getPackage, this method only parses the class name, without attempting to define the Package and hence load files. /**
   * 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
inter-operating 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/**
   * Ensures that the given classes are initialized, as described in <a
   * href="http://java.sun.com/docs/books/jls/third_edition/html/execution.html#12.4.2">JLS Section
   * 12.4.2</a>.
   *
   * <p>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
   * inter-operating 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 interfaceType by dispatching method invocations to handler. The class loader of interfaceType will be used to define the proxy class. To implement multiple interfaces or specify a class loader, use Proxy.newProxyInstance. 
Throws:
IllegalArgumentException – if interfaceType does not specify the type of a Java interface/**
   * 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> T newProxy(Class<T> 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() {}
}