Last Updated : 25 Nov, 2019
The firstKey() method of
SortedMap interface in Javais used to return the first or the lowest key currently in this map.
Syntax:
K firstKey()
Where, K is the type of key maintained by this Set.
Parameters: This function does not accepts any parameter.
Return Value: It returns the first print the lowest key currently in this map
Exception: It throws
NoSuchElementException, if this map is empty. Below programs illustrate the above method:
Program 1:
Java
// A Java program to demonstrate
// working of SortedMap
import java.util.*;
public class Main {
public static void main(String[] args)
{
// Create a TreeMap of SortedMap
SortedMap<Integer, String> mp = new TreeMap<>();
// Adding Element to SortedSet
mp.put(1, "One");
mp.put(5, "Five");
mp.put(2, "Two");
mp.put(3, "Three");
mp.put(9, "Nine");
// Returning the first key element
// from the map
System.out.print("First Key in the map : "
+ mp.firstKey());
}
}
Output:
First Key in the map : 1Program 2
:
Java
// A Java program to demonstrate
// working of SortedSet
import java.util.*;
public class Main {
public static void main(String[] args)
{
// Create a TreeSet and inserting elements
SortedMap<String, String> mp = new TreeMap<>();
// Adding Element to SortedSet
mp.put("One", "Geeks");
mp.put("Two", "For");
mp.put("Three", "Geeks");
mp.put("Four", "Code");
mp.put("Five", "It");
// Returning the first key
// from the map
System.out.print("First Key in the map is : "
+ mp.firstKey());
}
}
Output:
First Key in the map is : FiveReference
:
https://docs.oracle.com/javase/10/docs/api/java/util/SortedMap.html#firstKey()RetroSearch is an open source project built by @garambo | Open a GitHub Issue
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