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A set of utilities and tools to speed up and ease programming in Java.
There is a newer version: 0.5
/*
 * (c) 2005 David B. Bracewell
 *
 * 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
 *
 *   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.davidbracewell.conversion;


import com.davidbracewell.EnumValue;
import com.davidbracewell.logging.Logger;
import com.davidbracewell.reflection.Reflect;
import com.davidbracewell.reflection.ReflectionException;
import com.davidbracewell.reflection.ReflectionUtils;
import com.google.common.base.Function;
import com.google.common.base.Preconditions;

import java.util.Collection;
import java.util.Map;

/**
 *  Converter that tries to create a new object from the object it is given. 
  
 If the object is an
 * instance of the class, the object is cast and returned.
 If the object is of type Class, a new object is
 * created and returned if it is of the correct type, otherwise an exception thrown.
 If the object is a
 * string,
 * it is checked to see if it is a class name or static method name. If not, it will see if the class has a string
 * constructor.
 Last effort is to try and create the class with the object as the argument.
 
 
 *
 * @param  The type of object to create.
 * @author David B. Bracewell
 */
public class NewObjectConverter implements Function {

  private static final Logger log = Logger.getLogger(NewObjectConverter.class);


  private final Class convertToClass;

  public NewObjectConverter(Class convertToClass) {
    this.convertToClass = Preconditions.checkNotNull(convertToClass);
  }

  @Override
  @SuppressWarnings("unchecked")
  public T apply(Object obj) {

    if (convertToClass != Object.class && Convert.hasConverter(convertToClass)) {
      return Cast.as(Convert.convert(obj, convertToClass));
    } else if (Map.class.isAssignableFrom(convertToClass)) {
      return Cast.as(Convert.convert(obj, convertToClass, Object.class, Object.class));
    } else if (Collection.class.isAssignableFrom(convertToClass)) {
      return Cast.as(Convert.convert(obj, convertToClass, Object.class));
    } else if (convertToClass.isEnum()) {
      return Cast.as(Convert.convert(obj, Cast.>as(convertToClass)));
    }

    if (EnumValue.class.isAssignableFrom(convertToClass)) {
      if (obj.getClass().isAssignableFrom(convertToClass)) {
        return Cast.as(obj);
      } else if (obj instanceof CharSequence) {
        if (Reflect.onClass(convertToClass).containsMethod("create")) {
          try {
            return Reflect.onClass(convertToClass).invoke("create", obj.toString()).get();
          } catch (ReflectionException e) {

          }
        }

        try {
          return Reflect.onClass(convertToClass).allowPrivilegedAccess().create(obj.toString()).get();
        } catch (ReflectionException e) {

        }

      }
    }

    if (obj instanceof CharSequence) {
      Object o = ReflectionUtils.createObject(obj.toString());
      if (convertToClass.isInstance(o)) {
        return Cast.as(o);
      }
    }

    try {
      return Reflect.onClass(convertToClass).create(obj).get();
    } catch (ReflectionException e) {
      //ignore
    }

    log.fine("Could not convert {0} to {1}.", obj.getClass(), convertToClass);
    return null;
  }
}