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Java TreeMap navigableKeySet() Method with Example

TreeMap Class navigableKeySet() method: Here, we are going to learn about the navigableKeySet() method of TreeMap Class with its syntax and example.
Submitted by Preeti Jain, on February 29, 2020

TreeMap Class navigableKeySet() method

• navigableKeySet() method is available in java.util package.
• navigableKeySet() method is used to return a set of keys that exists in this TreeMap to be viewed in a NavigableSet.
• navigableKeySet() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• navigableKeySet() method does not throw an exception at the time of returning the navigable key set.

Syntax:

    public NavigableSet navigableKeySet();

Parameter(s):

• It does not accept any parameter.

Return value:

The return type of the method is NavigableSet, it returns contained set of keys in this TreeMap to be viewed in a NavigableSet.

Example:

// Java program to demonstrate the example 
// of NavigableSet navigableKeySet() method 
// of TreeMap 

import java.util.*;

public class NavigableKeySetOfTreeMap {
    public static void main(String[] args) {

        // Instantiates TreeMap
        TreeMap < Integer, String > tm = new TreeMap < Integer, String > ();

        // By using put() method is
        // to put the key-value pairs in
        // treemap tm
        tm.put(1, "C");
        tm.put(4, "C++");
        tm.put(3, "Java");
        tm.put(2, "Php");

        // Display TreeMap tm
        System.out.println("tm: " + tm);

        // By using navigableKeySet() method
        // is to return the set of keys exists
        // to be viewed in a NavigableSet

        // Display NavigableSet view
        System.out.println("tm.navigableKeySet(): " + tm.navigableKeySet());
    }
}

Output

tm: {1=C, 2=Php, 3=Java, 4=C++}
tm.navigableKeySet(): [1, 2, 3, 4]