AttributeImpl implements Attribute { @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append('['); sb.append(namespaceURI); sb.append("]:"); sb.append(name); sb.append("=\""); sb.append(value); sb.append('"'); return sb.toString(); } protected  AttributeImpl(String namespaceURI, String prefix, String name,
			String value); String getNamespaceUri(); String getPrefix(); String getName(); String getValue(); void setOwner(Element owner); Element getOwnerElement(); @Override int hashCode(); @Override boolean equals(Object obj); @Override String toString(); Object clone();  }
@Test public void testToString() { ConcreteAttributeImpl attr = new ConcreteAttributeImpl("ns", "pre", "name", "value"); attr.toString(); }