protected String checkHeap ( ) { for ( int i = 1 ; i < size ; i ++ ) { final int parent = ( i - 1 ) >>> 1 ; if ( comparator . compare ( queue [ parent ] , queue [ i ] ) > 0 ) { return "@" + parent + ": " + queue [ parent ] + " < @" + i + ": " + queue [ i ] ; } } return null ; }
Test whether the heap is still valid .