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TreeMap entrySet() Method in Java

  • Last Updated : 09 Jul, 2018

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:

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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() method
import 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() method
import 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.




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