code: public JSONBuilder array() {
        if( this.mode == 'i' || this.mode == 'o' || this.mode == 'a' ){
           this.push( 'a' );
           this.append( "[" );
           this.comma = false;
           return this;
        }
        throw new JSONException( "Misplaced array." );
     }
docs: Begin appending a new array. All values until the balancing
  <code>endArray</code> will be appended to this array. The
  <code>endArray</code> method must be called to mark the array's end.
  
  @return this
  @throws JSONException If the nesting is too deep, or if the object is
  started in the wrong place (for example as a key or after the end
  of the outermost array or object).