TreeMap : pollFirstEntry()

public Map.Entry<K,V> pollFirstEntry()

Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty.

import java.util.*;

class TreeMapPollFirstEntry{
 public static void main(String args[]){
  TreeMap<Integer, String> myMap;
  Map.Entry<Integer,String> firstEntry;
  
  myMap = new TreeMap<> ();
  
  /* Add Elements to myMap */
  myMap.put(2, "w");
  myMap.put(4, "wx");
  myMap.put(6, "wxy");
  myMap.put(8, "wxyz");
  
  System.out.println("Elements in myMap are");
  System.out.println(myMap);
  
  firstEntry = myMap.pollFirstEntry(); 
  
  System.out.println("First Entry in myMap is");
  System.out.println(firstEntry); 
  System.out.println("Elements in myMap are");
  System.out.println(myMap);  
 }
}

Output

Elements in myMap are
{2=w, 4=wx, 6=wxy, 8=wxyz}
First Entry in myMap is
2=w
Elements in myMap are
{4=wx, 6=wxy, 8=wxyz}

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