The java.util.TreeMap.entrySet() method in Java is used to create a set out of the same elements contained in the treemap. It basically returns a set view of the treemap or we can create a new set and store the map elements into them.
Syntax:
tree_map.entrySet()
Parameters: The method does not take any parameter.
Return Value: The method returns a set having same elements as the treemap.
Below programs are used to illustrate the working of java.util.TreeMap.entrySet() Method:
Program 1: Mapping String Values to Integer Keys.
// Java code to illustrate the entrySet() methodimport java.util.*;  public class Tree_Map_Demo {    public static void main(String[] args)    {          // Creating an empty TreeMap        TreeMap<Integer, String> tree_map = new TreeMap<Integer, String>();          // Mapping string values to int keys        tree_map.put(10, "Geeks");        tree_map.put(15, "4");        tree_map.put(20, "Geeks");        tree_map.put(25, "Welcomes");        tree_map.put(30, "You");          // Displaying the TreeMap        System.out.println("Initial Mappings are: " + tree_map);          // Using entrySet() to get the set view        System.out.println("The set is: " + tree_map.entrySet());    }} |
Output:
Initial Mappings are: {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
The set is: [10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You]
Program 2: Mapping Integer Values to String Keys.
// Java code to illustrate the entrySet() methodimport java.util.*;  public class Tree_Map_Demo {    public static void main(String[] args)    {          // Creating an empty TreeMap        TreeMap<String, Integer> tree_map = new TreeMap<String, Integer>();          // Mapping int values to string keys        tree_map.put("Geeks", 10);        tree_map.put("4", 15);        tree_map.put("Geeks", 20);        tree_map.put("Welcomes", 25);        tree_map.put("You", 30);          // Displaying the TreeMap        System.out.println("Initial Mappings are: " + tree_map);          // Using entrySet() to get the set view        System.out.println("The set is: " + tree_map.entrySet());    }} |
Output:
Initial Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
The set is: [4=15, Geeks=20, Welcomes=25, You=30]
Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.
