In this shot, we will learn how to use the **`TreeMap.pollFirstEntry()`** method in Java.

#   
## Introduction
The `TreeMap.pollFirstEntry()` method is present in the `NavigableSet` interface inside the `java.util` package. The `TreeMap` class implements the `NavigableSet` interface.

`TreeMap.pollFirstEntry()` is used to retrieve and remove the key-value pair, where the key is the lowest key present in the map.

## Syntax
The syntax of the `TreeMap.pollFirstEntry()` method is shown below:



#    
## Parameters
`TreeMap.pollFirstEntry()` does not accept any parameters.

## Return value
The `TreeMap.pollFirstEntry()` method returns the key-value pair with the smallest key value from the map.

## Code
Let’s have a look at the code.

import java.util.*;
class Main 
{
  public static void main(String[] args)
  {
    TreeMap<Integer, String> t1 = new TreeMap<Integer, String>();

    t1.put(1, "Learn");
    t1.put(5, "in-demand");
    t1.put(2, "tech skills");
    t1.put(27, "on");
    t1.put(9, "Educative.io");

    System.out.println("The removed element from the TreeMap" + 
      "after using pollFirstEntry() is: " + t1.pollFirstEntry());
  }
}

#    
## Explanation
* In line 1, we import the required package.
* In line 2, we make a `Main` class.
* In line 4, we make a `main()` function.

* In line 6, we declare a `TreeMap` that consists of keys of type `Integer` and values of type `String`.
* From lines 8 to 12, we use the `TreeMap.put()` method to insert values in the `TreeMap`.
* In line 14, we use the `TreeMap.pollFirstEntry()` method and display the removed key-value value from the map with a message.






What is the TreeMap.pollFirstEntry() method in Java?

TreeMap.pollFirstEntry() retrieves and removes the key-value pair with the smallest key in the map.