content: /*
   * Copyright (C) 2017 The Android Open Source Project
   *
   * 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.
   */
  
  import java.lang.reflect.Field;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.util.List;
  
  class MyClassLoader extends ClassLoader {
    MyClassLoader() throws Exception {
      super(MyClassLoader.class.getClassLoader());
  
      // Some magic to get access to the pathList field of BaseDexClassLoader.
      ClassLoader loader = getClass().getClassLoader();
      Class<?> baseDexClassLoader = loader.getClass().getSuperclass();
      Field f = baseDexClassLoader.getDeclaredField("pathList");
      f.setAccessible(true);
      Object pathList = f.get(loader);
  
      // Some magic to get access to the dexField field of pathList.
      f = pathList.getClass().getDeclaredField("dexElements");
      f.setAccessible(true);
      dexElements = (Object[]) f.get(pathList);
      dexFileField = dexElements[0].getClass().getDeclaredField("dexFile");
      dexFileField.setAccessible(true);
    }
  
    Object[] dexElements;
    Field dexFileField;
  
    protected Class<?> loadClass(String className, boolean resolve) throws ClassNotFoundException {
      // Mimic what DexPathList.findClass is doing.
      try {
        for (Object element : dexElements) {
          Object dex = dexFileField.get(element);
          Method method = dex.getClass().getDeclaredMethod(
              "loadClassBinaryName", String.class, ClassLoader.class, List.class);
  
          if (dex != null) {
            Class<?> clazz = (Class<?>)method.invoke(dex, className, this, null);
            if (clazz != null) {
              return clazz;
            }
          }
        }
      } catch (InvocationTargetException ite) {
        throw new ClassNotFoundException(className, ite.getCause());
      } catch (Exception e) {
        throw new Error(e);
      }
      return getParent().loadClass(className);
    }
  }
  
  public class Main {
    public static void main(String[] args) throws Exception {
      MyClassLoader o = new MyClassLoader();
      try {
        Class<?> foo = o.loadClass("Main");
        throw new Error("Unreachable");
      } catch (ClassNotFoundException cnfe) {
        boolean unexpected = false;
        if (!(cnfe.getCause() instanceof InternalError)) {
          unexpected = true;
        } else {
          String message = cnfe.getCause().getMessage();
          unexpected = !message.startsWith("Attempt to register dex file ") ||
                       !message.endsWith(" with multiple class loaders");
        }
        if (unexpected) {
          cnfe.getCause().printStackTrace();
        }
      }
    }
  }
  