At most one null key and numerous null values may be stored in a hash map. TreeMap, on the other hand, does not permit a null key but may contain numerous null values
A method for visualizing big, hierarchical data sets is the use of treemaps. The worth of each data point and the hierarchy's structure are two different sorts of information that they extract from the data.
Java's TreeSet class implements SortedSet. Java's TreeMap class implements the Map Interface. Java's TreeSet only kept one item in storage. Two objects—one key and one value—are stored in a TreeMap.
Select Treemap from the Insert tab on the ribbon after clicking the Hierarchy symbol. To change the appearance of your chart, use the Chart Design and Format tabs. Click anywhere on the Treemap chart to activate these tabs if you can't see them.
With the help of treemaps, readers may quickly and easily analyze their data. Dimensions or measurements can be represented by a color (such as KPIs). If a KPI is being shown, a deeper hue may draw attention to extremes, either high or low.