PropertyUtil.java

/*  Copyright (c) 2000-2006 hamcrest.org
 */
package org.hamcrest.beans;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;

/**
 * Utility class for accessing properties on JavaBean objects.
 * <p/>
 * See http://java.sun.com/products/javabeans/docs/index.html for
 * more information on JavaBeans.
 *
 * @author Iain McGinniss
 * @author Steve Freeman
 * @since 1.1.0
 */
public class PropertyUtil {
    /**
     * Returns the description of the property with the provided
     * name on the provided object's interface.
     *
     * @return the descriptor of the property, or null if the property does not exist.
     * @throws IllegalArgumentException if there's a introspection failure
     */
    public static PropertyDescriptor getPropertyDescriptor(String propertyName, Object fromObj) throws IllegalArgumentException {
        for (PropertyDescriptor property : propertyDescriptorsFor(fromObj, null)) {
            if (property.getName().equals(propertyName)) {
                return property;
            }
        }

        return null;
    }

    /**
     * Returns all the property descriptors for the class associated with the given object
     * 
     * @param fromObj Use the class of this object
     * @param stopClass Don't include any properties from this ancestor class upwards.
     * @return Property descriptors
     * @throws IllegalArgumentException if there's a introspection failure
     */
    public static PropertyDescriptor[] propertyDescriptorsFor(Object fromObj, Class<Object> stopClass) throws IllegalArgumentException {
      try {
        return Introspector.getBeanInfo(fromObj.getClass(), stopClass).getPropertyDescriptors();
      } catch (IntrospectionException e) {
        throw new IllegalArgumentException("Could not get property descriptors for " + fromObj.getClass(), e);
      }
    }

    public static final Object[] NO_ARGUMENTS = new Object[0];
}