code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC 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.
  
  package org.openqa.selenium.support.pagefactory;
  
  import java.lang.annotation.Annotation;
  import java.lang.reflect.Field;
  import org.openqa.selenium.By;
  import org.openqa.selenium.support.AbstractFindByBuilder;
  import org.openqa.selenium.support.ByIdOrName;
  import org.openqa.selenium.support.CacheLookup;
  import org.openqa.selenium.support.FindAll;
  import org.openqa.selenium.support.FindBy;
  import org.openqa.selenium.support.FindBys;
  import org.openqa.selenium.support.PageFactoryFinder;
  
  public class Annotations extends AbstractAnnotations {
    private Field field;
  
    /**
     * @param field expected to be an element in a Page Object
     */
    public Annotations(Field field) {
      this.field = field;
    }
  
    /**
     * {@inheritDoc}
     *
     * @return true if @CacheLookup annotation exists on a field
     */
    @Override
    public boolean isLookupCached() {
      return (field.getAnnotation(CacheLookup.class) != null);
    }
  
    /**
     * {@inheritDoc}
     *
     * <p>Looks for one of {@link org.openqa.selenium.support.FindBy}, {@link
     * org.openqa.selenium.support.FindBys} or {@link org.openqa.selenium.support.FindAll} field
     * annotations. In case no annotations provided for field, uses field name as 'id' or 'name'.
     *
     * @throws IllegalArgumentException when more than one annotation on a field provided
     */
    @Override
    public By buildBy() {
      assertValidAnnotations();
  
      By ans = null;
  
      for (Annotation annotation : field.getDeclaredAnnotations()) {
        AbstractFindByBuilder builder = null;
        if (annotation.annotationType().isAnnotationPresent(PageFactoryFinder.class)) {
          try {
            builder =
                annotation
                    .annotationType()
                    .getAnnotation(PageFactoryFinder.class)
                    .value()
                    .getDeclaredConstructor()
                    .newInstance();
          } catch (ReflectiveOperationException e) {
            // Fall through.
          }
        }
        if (builder != null) {
          ans = builder.buildIt(annotation, field);
          break;
        }
      }
  
      if (ans == null) {
        ans = buildByFromDefault();
      }
  
      return ans;
    }
  
    protected Field getField() {
      return field;
    }
  
    protected By buildByFromDefault() {
      return new ByIdOrName(field.getName());
    }
  
    protected void assertValidAnnotations() {
      FindBys findBys = field.getAnnotation(FindBys.class);
      FindAll findAll = field.getAnnotation(FindAll.class);
      FindBy findBy = field.getAnnotation(FindBy.class);
      if (findBys != null && findBy != null) {
        throw new IllegalArgumentException(
            "If you use a '@FindBys' annotation, " + "you must not also use a '@FindBy' annotation");
      }
      if (findAll != null && findBy != null) {
        throw new IllegalArgumentException(
            "If you use a '@FindAll' annotation, " + "you must not also use a '@FindBy' annotation");
      }
      if (findAll != null && findBys != null) {
        throw new IllegalArgumentException(
            "If you use a '@FindAll' annotation, " + "you must not also use a '@FindBys' annotation");
      }
    }
  }
  