function toString() {
  return this.layout().join("");
  }
Returns the <code>BigDecimal</code> as a <code>String</code>.
This returns a <code>String</code> that exactly represents this
<code>BigDecimal</code>, as defined in the decimal documentation
(see {@link BigDecimal class header}).
<p>
By definition, using the {@link #BigDecimal(String)} constructor
on the result <code>String</code> will create a
<code>BigDecimal</code> that is exactly equal to the original
<code>BigDecimal</code>.

@return The <code>String</code> exactly corresponding to this
        <code>BigDecimal</code>.
@see    #format(int, int)
@see    #format(int, int, int, int, int, int)
@see    #toCharArray()
@stable ICU 2.0