Last Updated : 11 Jul, 2025
The firstEntry() method of
NavigableMap interface in Javais used to return a key-value mapping associated with the least key in this map, or null if the map is empty.
Syntax:
Map.Entry< K, V > firstEntry()
Where, K is the type of key maintained by this map and V is the type of values mapped to the keys.
Parameters: It does not accepts any parameter.
Return Value: It returns a key-value mapping associated with the least key in this map, or null if the map is empty. Below programs illustrate the firstEntry() method in Java:
Program 1: When the key is integer.
Java
// Java code to demonstrate the working of
// firstEntry() method
import java.io.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the NavigableMap of Integer and String
NavigableMap<Integer, String> nmmp = new TreeMap<>();
// assigning the values in the NavigableMap
// using put()
nmmp.put(2, "two");
nmmp.put(7, "seven");
nmmp.put(3, "three");
System.out.println("The mapping with least key is : "
+ nmmp.firstEntry());
}
}
Output:
The mapping with least key is : 2=twoProgram 2
: When the key is string.
Java
// Java code to demonstrate the working of
// firstEntry() method
import java.io.*;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// Declaring the NavigableMap of Integer and String
NavigableMap<String, String> tmmp = new TreeMap<>();
// assigning the values in the NavigableMap
// using put()
tmmp.put("one", "two");
tmmp.put("six", "seven");
tmmp.put("two", "three");
System.out.println("The mapping associated with least key is : "
+ tmmp.firstEntry());
}
}
Output:
The mapping associated with least key is : one=twoReference
:
https://docs.oracle.com/javase/10/docs/api/java/util/NavigableMap.html#firstEntry()RetroSearch is an open source project built by @garambo | Open a GitHub Issue
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