Java AbstractMap toString method

package java.util;

public abstract class AbstractMap<K,V> implements Map<K,V> {

    /**
     * Returns a string representation of this map.  The string representation
     * consists of a list of key-value mappings in the order returned by the
     * map's <tt>entrySet</tt> view's iterator, enclosed in braces
     * (<tt>"{}"</tt>).  Adjacent mappings are separated by the characters
     * <tt>", "</tt> (comma and space).  Each key-value mapping is rendered as
     * the key followed by an equals sign (<tt>"="</tt>) followed by the
     * associated value.  Keys and values are converted to strings as by
     * {@link String#valueOf(Object)}.
     *
     * @return a string representation of this map
     */
    public String toString() {
        Iterator<Entry<K,V>> i = entrySet().iterator();
        if (! i.hasNext())
            return "{}";

        StringBuilder sb = new StringBuilder();
        sb.append('{');
        for (;;) {
            Entry<K,V> e = i.next();
            K key = e.getKey();
            V value = e.getValue();
            sb.append(key   == this ? "(this Map)" : key);
            sb.append('=');
            sb.append(value == this ? "(this Map)" : value);
            if (! i.hasNext())
                return sb.append('}').toString();
            sb.append(',').append(' ');
        }
    }

}