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: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
// 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
// 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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