private E firstDataItem ( ) { for ( Node p = head ; p != null ; p = succ ( p ) ) { Object item = p . item ; if ( p . isData ) { if ( item != null && item != p ) return LinkedTransferQueue . < E > cast ( item ) ; } else if ( item == null ) return null ; } return null ; }
Returns the item in the first unmatched node with isData ; or null if none . Used by peek .