question: public boolean check ( ) { if ( childNodes == null ) { return true ; } int siblingElementIndex = 0 ; for ( int i = 0 , childNodesSize = childNodes . size ( ) ; i < childNodesSize ; i ++ ) { Node childNode = childNodes . get ( i ) ; if ( childNode . siblingIndex != i ) { return false ; } if ( childNode . getNodeType ( ) == NodeType . ELEMENT ) { if ( childNode . siblingElementIndex != siblingElementIndex ) { return false ; } siblingElementIndex ++ ; } } if ( childElementNodesCount != siblingElementIndex ) { return false ; } if ( childElementNodes != null ) { if ( childElementNodes . length != childElementNodesCount ) { return false ; } int childCount = getChildNodesCount ( ) ; for ( int i = 0 ; i < childCount ; i ++ ) { Node child = getChild ( i ) ; if ( child . siblingElementIndex >= 0 ) { if ( childElementNodes [ child . siblingElementIndex ] != child ) { return false ; } } } } if ( siblingNameIndex != - 1 ) { List < Node > siblings = parentNode . childNodes ; int index = 0 ; for ( int i = 0 , siblingsSize = siblings . size ( ) ; i < siblingsSize ; i ++ ) { Node sibling = siblings . get ( i ) ; if ( sibling . siblingNameIndex == - 1 && nodeType == NodeType . ELEMENT && nodeName . equals ( sibling . getNodeName ( ) ) ) { if ( sibling . siblingNameIndex != index ++ ) { return false ; } } } } for ( Node childNode : childNodes ) { if ( ! childNode . check ( ) ) { return false ; } } return true ; }
target:  Checks the health of child nodes. Useful during complex tree manipulation, to check if everything is OK. Not optimized for speed, should be used just for testing purposes.