Last Updated : 17 Sep, 2018
The java.util.concurrent.ConcurrentLinkedDeque.getFirst() method is an in-built method in Java which returns the first element of the deque container.
Syntax:Conn_Linked_Deque.getFirst()Parameters:
The method does not accept any parameter.
Return Value:The method returns the first element present in the Deque.
Exception:The function throws a
NoSuchElementExceptionwhen the deque is empty. Below programs illustrate the ConcurrentLinkedDeque.getFirst() method :
Program 1:
Java
/* Java Program to Demonstrate getFirst()
method of ConcurrentLinkedDeque */
import java.util.concurrent.*;
class GFG {
public static void main(String[] args)
{
// Creating an empty Deque
ConcurrentLinkedDeque<String> cld =
new ConcurrentLinkedDeque<String>();
// Add elements into the Deque
cld.add("Welcome");
cld.add("To");
cld.add("Geeks");
cld.add("4");
cld.add("Geeks");
// Displaying the Deque
System.out.println("Elements in the Deque: " + cld);
// Displaying the first element
System.out.println("The first element is: " +
cld.getFirst());
}
}
Output:
Elements in the Deque: [Welcome, To, Geeks, 4, Geeks] The first element is: WelcomeProgram 2: Java
/* Java Program to Demonstrate getFirst()
method of ConcurrentLinkedDeque */
import java.util.concurrent.*;
class GFG {
public static void main(String[] args)
{
// Creating an empty Deque
ConcurrentLinkedDeque<Integer> cld =
new ConcurrentLinkedDeque<Integer>();
try {
// Displaying the first element
System.out.println("The first element "
+ "is: " + cld.getFirst());
}
catch (Exception e) {
System.out.println(e);
}
// Add elements into the Deque
cld.add(12);
cld.add(43);
cld.add(29);
cld.add(16);
cld.add(70);
// Displaying the Deque
System.out.println("Elements in the Deque: " + cld);
// Displaying the first element
System.out.println("The first element is: " +
cld.getFirst());
}
}
Output:
java.util.NoSuchElementException Elements in the Deque: [12, 43, 29, 16, 70] The first element is: 12Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentLinkedDeque.html#getFirst()
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