001    /**
002     * 
003     */
004    package org.springframework.binding.value.support;
005    
006    import org.springframework.binding.value.ValueChangeDetector;
007    
008    /**
009     * An implementation of ValueChangeDetector that provides the same semantics as
010     * {@link org.springframework.util.ObjectUtils#nullSafeEquals(java.lang.Object, java.lang.Object)}.
011     * If the objects are not the same object, they are compared using the equals method of
012     * the first object. Nulls are handled safely.
013     * 
014     * @author Larry Streepy
015     * 
016     */
017    public class EqualsValueChangeDetector implements ValueChangeDetector {
018    
019        /**
020         * Determines if there has been a change in value between the provided arguments. The
021         * objects are compared using the <code>equals</code> method.
022         * 
023         * @param oldValue Original object value
024         * @param newValue New object value
025         * @return true if the objects are different enough to indicate a change in the value
026         *         model
027         */
028        public boolean hasValueChanged(Object oldValue, Object newValue) {
029            return !(oldValue == newValue || (oldValue != null && oldValue.equals( newValue )));
030        }
031    }