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'databene commons' is an open source Java library by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.
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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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 org.databene.commons.converter;

import org.databene.commons.ArrayUtil;
import org.databene.commons.BeanUtil;

import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.util.Collection;

/**
 * Converts arrays and collections to arrays and other object to an array of size 1.
 * Note: The target type is not declared Object[], since we also want to create byte[].
 * Created: 26.08.2007 16:01:38
 * @author Volker Bergmann
 */
@SuppressWarnings({ "unchecked", "rawtypes" })
public class ToArrayConverter extends ThreadSafeConverter {

    private Class componentType;
    private boolean nullToEmpty;

    // constructors ----------------------------------------------------------------------------------------------------
    
    public ToArrayConverter() {
        this(Object.class);
    }

    public ToArrayConverter(Class componentType) {
        this(componentType, true);
    }

    public ToArrayConverter(Class componentType, boolean nullToEmpty) {
    	super(Object.class, ArrayUtil.arrayType(componentType));
        this.componentType = componentType;
        this.nullToEmpty = nullToEmpty;
    }
    
    // properties ------------------------------------------------------------------------------------------------------

    public void setNullToEmpty(boolean nullToEmpty) {
    	this.nullToEmpty = nullToEmpty;
    }

    // Converter interface implementation ------------------------------------------------------------------------------

    @Override
	public Object convert(Object sourceValue) {
        return convert(sourceValue, componentType, nullToEmpty);
    }
    
    // static utility methods ------------------------------------------------------------------------------------------

    public static Object convert(Object sourceValue, Class componentType) {
    	return convert(sourceValue, componentType, true);
    }

    @SuppressWarnings("cast")
    public static Object convert(Object sourceValue, Class componentType, boolean nullToEmpty) {
    	if (sourceValue == null)
    		return (nullToEmpty ? ArrayUtil.buildArrayOfType(componentType) : null);
        if (sourceValue instanceof Collection) {
            Collection col = (Collection) sourceValue;
            Object[] array = (Object[]) Array.newInstance(componentType, col.size());
            int count = 0;
            for (Object item : col)
                array[count++] = item;
            return array;
        } else if (componentType == byte.class) {
            Method method = BeanUtil.getMethod(sourceValue.getClass(), "getBytes");
            if (method != null)
                return (byte[]) BeanUtil.invoke(sourceValue, method, null);
            else
                throw new UnsupportedOperationException("Conversion not supported: " + sourceValue.getClass() + " -> " + componentType + "[]");
        } else if (sourceValue.getClass().isArray()) {
            return ArrayUtil.buildArrayOfType(componentType, (Object[]) sourceValue);
	    } else  {
	        return ArrayUtil.buildArrayOfType(componentType, sourceValue);
	    }
    }

    @Override
    public String toString() {
    	return getClass().getSimpleName() + "(" + componentType + ")";
    }
    
}