hash tables the fill button initiallythe hash table contains itemsso it' half full howeveryou can also fill it with specified number of data items using the fill button keep clicking filland when promptedtype the number of items to fill hash tables work best when they are not more than half or at the most two-thirds full ( items in -cell tableyou'll see that the filled cells aren' evenly distributed in the cells sometimes there' sequence of several empty cells and sometimes sequence of filled cells let' call sequence of filled cells in hash table filled sequence as you add more and more itemsthe filled sequences become longer this is called clusteringand is shown in figure cluster figure an example of clustering when you use the appletnote that it may take long time to fill hash table if you try to fill it too full (for exampleif you try to put items in -cell tableyou may think the program has stoppedbut be patient it' extremely inefficient at filling an almost-full array